And don't forget to consider things like gas and stuff in your pricing. I mean, even if you just save, say, $20 a week in gas, a $200 bike is going to pay for itself entirely in less than 3 months.

Well, the bike itself, not counting maintenance, accessories, etc. etc. etc...But the point is, if you've got a little cash or savings floating around, even just dropping down to car-light could make it work out in your favor.

Of course, this is coming from another newbie, both to here and to the whole cycling thing proper(as opposed to pedaling around as a kid for fun once every once in a while), so take my advice with a grain of salt, and good luck.