Unless you’ve been holed up in a cave somewhere, you’re probably aware that oil prices have been going through the roof: A barrel of black gold closed north of $136 in Tuesday's trading. Not surprisingly, many investors have been flocking to alternative energy and solar stocks with the the expectation that businesses and consumers may soon be clamoring for all things green.

Some of the big winners of late include First Solar (FSLR), which sells solar power modules, and SunPower (SPWR), which manufactures solar cells, panels and the like. For those keeping score, First Solar’s stock has soared from around $30 to around $250 since the beginning of 2007. SunPower’s shares have moved from the mid-$30 level to the mid-$70 level in the same period.

But are these and other tree huggers really the best play right now?

First, consumers and companies (particularly large ones) aren't typically given to overnight change. Widespread acceptance of what is still by and large perceived as a newfangled technology could take some time.

Second, there's the initial outlay to acquire panels and other gadgetry necessary to harness the power of sunlight. Outfitting a home with all the bells and whistles can literally run well into the thousands. And given the high cost of food and gas (which we still need), many families don’t seem to have that kind of dough to plunk down these days.

Third, it generally takes a while for the individual or business to break even on their investment, and frankly consumers in this country aren't known for their patience or ability to think long term.

Fourth, there’s the issue of valuation. Some perspective: First Solar earned about $158.4 million in 2007, yet the company sports a market cap of almost $20.2 billion. Meanwhile, SunPower generated a whopping $9.2 million in net income in 2007 with a roughly $6.2 billion market cap. Seeing this, legendary value investor Ben Graham is no doubt turning in his grave right now.

On the flip side, one could make the case that automakers are a good play. After all, some have valuable assets on their balance sheets (cash and property) and expectations for the sector are low. They're also slowly but surely -- as opposed to full force -- going green.

General Motors (GM), for example, which has its share of gas guzzlers, has already worked a hybrid Tahoe and Yukon into its repertoire. And Toyota (TM) just announced plans to add two new hybrids (one Toyota, one Lexus) to its lineup.

Look, going green is a great idea, but it takes time and money to make it happen. And while consumers and companies may have plenty of the former, right now it’s the latter they seem to be lacking. Coupled with the lofty valuations we're seeing in alternative energy stocks, it makes me wonder it it's too late to jump on the bandwagon.

For more on energy, check out Hoofy & Boo's always astute report: