Fools Isaac Pino and Matt Thalman discuss one key investing point that both new and old investors need to keep in mind when searching for stocks to buy.

The "sticker shock" of such high-profile companies as Google (NASDAQ:GOOGL), which trades at $810 per share, and Apple (NASDAQ:AAPL), which trades at $450 a share, can turn investors off and lead them to miss a great opportunity. But a high share price alone doesn't mean a stock is expensive or that the price can't go higher in the future.

One metric investors should be looking at is the price-to-earnings ratio. Google trades at a P/E ratio of 25, while Apple is even cheaper, at only 10. Compare that with 3D Systems (NYSE:DDD), which has a shares price of only $31 but trades at a P/E of 66.

In Apple's case, an investor is paying $10 for $1 worth of earnings. With Google, it's slightly more expensive, at $25 for every $1 of current earnings. With this sort of thinking, 3D Systems' $31 share price doesn't look cheap anymore, even though it is 14 times less expensive on a dollar basis than Apple.

One more thing to remember is that a 10% return on $2,000 in Google is the same as a 10% return on $2,000 in a $31 per share stock. What you must determine is this: Which one carries more risk?

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.