Determining the price of a publicly traded company seems simple enough. Multiply the stock price by the number of outstanding shares. Google costs about $156 billion. Verizon goes for around $83 billion.

However, companies aren't like cans of peas. They have something called a capital structure, which can make the true cost of owning them, free and clear, differ sharply from the sticker price. Verizon owes billions. Add the cost of repaying that debt to the stock price and the result is an "enterprise value," or true purchase price, of $140 billion. Google owes nothing and hoards cash, so what seems like the more expensive company is actually the cheaper one, with an enterprise price of $129 billion.

Capital structure should matter as much to small-stake investors as to corporate raiders, because the merits of buying a few shares of a company are similar to those of buying all the shares. The companies below all have price/sales ratios that are below their industry averages, making them appear inexpensive. Their enterprise-value/sales ratios, however, are sharply higher. That doesn't mean investors should ignore them altogether, but it does mean they should carefully consider the full costs when deciding whether to buy.

Constellation Brands

Price/sales: 1.0
Industry price/sales: 2.2
EV/sales: 2.2

Booze has long been considered recession-resistant, but that was before U.S. drinkers went upscale, swapping cheap pilsner for microbrews; nondescript firewater for infused vodkas and sipping tequilas; and just about everything else for wine. Now distributors can and do suffer slumps when consumer spending contracts. Sales for Constellation Brands, which makes most of its money from wine, fell 8% during its fiscal year ended in February. Worse, the company paid dearly for Robert Mondavi and Vincor, vintners in California and Canada, respectively, in 2006, when the nation was toasting its raging house prices. Shares today sell for about 40% less than they did then, and they look plenty cheap relative to sales and earnings, but debt could restrain the company's returns on invested capital for years to come.

Sprint Nextel

Price/sales: 0.4
Industry price/sales: 4.7
EV/sales: 0.9

AT&T has an exclusive service contract for Apple popular iPhone. Verizon is widely believed to lead the market in call quality. Sprint Nextel has perhaps the beginnings of a turnaround to boast about, but not much else. It's market share of contract cell phone customers is about 18%, up from 12% a year ago (following widespread service complaints), but down from more than 25% at the company's peak, according to Morningstar Equity Research. The company earns barely one-third what Verizon does in adjusted operating income per customer. That suggests the company has plenty of room for improvement but also less of an ability than peers to endure a prolonged industry downturn, if there is one, while investing in next-generation wireless infrastructure.

Dean Foods

Price/sales: 0.2
Industry price/sales: 1.4
EV/sales: 0.5

Marketers have managed to brand and charge dearly for some surprising goods in recent decades, including water, coffee and, as already mentioned, formerly conventional liquor. Milk has defied the best of them, however. Customers tend to buy it based on fat percentage, not dairy name. Grocers, who are aware that any regular shopper knows the precise cost of milk, often sell it for little profit. As a result, the nation's largest milk producer, Dean Foods, turns just a nickel of each sales dollar into operating profit, versus more than a dime for packaged food sellers like Kraft and J.M. Smucker. By the time financing and other costs are taken out, Dean's net profit is just two cents on the dollar. The company has reduced its debt in recent years but still owes plenty, and in recent quarters it has missed Wall Street's profit forecasts by double-digit percentages -- generally a poor sign.