One of the challenges of buying an industry leader such as Apple (Nasdaq: AAPL) is that it is “priced to perfection.” The value of its stock implies that the company will fulfill all of the high expectations placed upon it. More than likely, Apple will keep on delivering winning products, but that would be a surprise to almost no one. So it’s hard to see how any more good news is not yet built into the stock. For example, few expect shares to gain a major boost when the next iPhone is released on June 24. Its success is already expected.

But what about Apple’s rivals, who have sat idly by and missed out on the technology revolution that Apple has pioneered? Few expect these rivals to get a major slice of mobile device market, so they are “priced to imperfection.” Yet as we saw with Nokia (NYSE: NOK) a decade ago, and Motorola (NYSE: MOT) five years ago, these lagging rivals can sometimes get it right, and when they do, shares can zoom ahead.

With that in mind, here’s a look at what these firms are cooking up, and how you can invest in the space.

Dell (Nasdaq: DELL)

Dell is among a number of companies that have announced plans to come up with a rival for either the iPhone or the iPad. In Dell’s case the company is going after both markets by offering a product that slots somewhere in between. The company’s Streak is already selling in the United Kingdom, and will be launched in the United States later this summer. By Labor Day, we’ll know if consumers see the product as the best of both worlds or the worst of both worlds. It’s about 30% smaller than an iPad, which makes it difficult to use as an electronic reader, and with a 5.25-inch screen, it may be too big to use as a daily cellphone. Then again, it’ll be easier to lug around than an iPad. And you can use it make calls.

Of course, the success or failure of such a device depends on how many apps it can run. If Dell were to try to build a base of apps from scratch, it would never catch up to Apple. Wisely, the device runs on Google’s (Nasdaq: GOOG) Android operating system, which is becoming more popular by the month with app developers. A range of hardware vendors are coalescing behind Android, increasing the odds that it will end up creating a pool of apps — and users — to rival the massive iPad/iPhone community.

For Dell, the Streak is unlikely to be a game changer even if successful, because it will still represent a fraction of its overall hardware business. But the device could serve as a halo product for the rest of Dell’s offerings, making the company relevant once again in the consumer space.

Dell’s positioning among businesses remains fairly strong. The company’s line of high-end PCs, servers, storage devices, and other enterprise-focused wares may not have shown much growth in recent years, but is still a massive cash generator. Dell generated about $3 billion in operating income in calendar 2009, and the current year is already off to a good start. If companies start to more aggressively invest in the latest Windows operating system, then cash flow should approach $4 billion by next year. The new Streak, to the extent that it energizes the consumer business, could push cash flow up another +20% by 2012 or 2013. And that would lead to Dell once again being seen as a growth stock, and finally start to generate a price-to-earnings ratio (P/E) closer to high-flying Apple.

Right now, shares of Dell trade for around nine times fiscal (January) 2012 profits. And the multiple is well lower when Dell’s $5 billion growing cash pile is excluded. In contrast, Apple’s P/E multiple is around 20 (on a fiscal year that ends four months earlier. Here again the multiple is lower when cash is excluded). If Dell could simply justify a forward P/E ratio closer to 12 or 13, then investors would be looking at a +30% to +40% gain.

Motorola (NYSE: MOT)

The Motorola RAZR was an immediate sensation when launched, pushing shares north of $25 in 2006. These days, shares are off nearly -75% from that peak, as it’s been a long time since Motorola led the mobile device market. Motorola is trying to regain some buzz, and its recent Android-based phones are selling fairly well and carrying impressive gross margins. But Motorola has yet to show its hand in the iPhone/iPad market. Rumors abound that it will unveil an iPad-like device later this year, but it’s unclear if the company has any brand loyalty left with consumers.

Motorola has plans to spin off its mobile devices unit, and management has expressed hopes of creating some buzz for the division prior to any spin-off. In the meantime, shares mark time in the $7 range, 15% to 25% below where analysts expect the stock to land once the spinoff plans come into sharper focus. Shares have probably found a floor in the current range, and any new iPad-like device might help to give a short-term boost, though it’s worth noting that Dell’s announcement of the Streak failed to move shares much higher. As of now, investors remain convinced that Apple has sewn up this market lock, stock and barrel.

Nokia (NYSE: NOK)

Once-mighty Nokia has been a real disappointment for its backers, with its U.S. market share rapidly shrinking and its European market share in steady decline. Make no mistake, the company has an impressively broad array of mobile devices, is still a powerful brand name across Asia, Latin America and Africa, and has strong relationships with many wireless carriers. But the company made a mistake by sticking with an operating system known as Symbian, while Apple and Google’s software has proven to be far more robust. The odds of a rich community of applications developers coalescing around Symbian hover between slim and none.

Nokia has emerged as a low-cost producer, which allows it to offer very inexpensive phones in price-sensitive markets, but the company seemingly chose to focus on the wrong end of the market. Ten years ago, Nokia dwarfed Apple in terms of market value. By developing sophisticated products with very consumer-friendly software, Apple has generated so much buzz that it now has a market value seven times that of Nokia.

In recent quarters, Nokia’s management has poured more resources into R&D, vowing to once again become relevant in the smartphone market. You can’t count them out. As this analysis has shown, every dog has its day in this market. But it is hard to see how Apple will lose its way at this point. Instead, investors should focus on which of the companies can show some momentum. They’ve all done it before.

Action to Take –> Shares of Apple are quite pricey compared with the rest of these firms, by a range of valuation metrics. Dell, Motorola and Nokia all have real attributes, and not many supporters. Rather than try to pick a winner among the group, investors may want to spread the wealth around, building small positions in all three. Even if only one of them develops a hot product to rival the iPad/iPhone, the value of the basket of stocks would rise smartly. And if none of these stocks makes a major splash, shares are still likely to find support thanks to strong balance sheets and strong cash flow generation.