My favorite protip for Craigslist is to search for the word "thought", and turn up tons of ads from guys who say things like "I bought this super-expensive bike because I thought I would get into road biking, but I didn't, so now you can buy this bike for half what I paid, and it only has 100 miles on it, so basically it's brand-new"

So since you anticipate that you might be (become) that guy, you have the opportunity to instead take advantage of that guy. Look on Craigslist in your price range, or $100-200 below your price range (to allow for cost of tuning/accesories like lights, new tires, etc). If you see some bikes that look interesting, drop some links here in this thread, we love looking at bikes and telling people what we think!

And if you do decide in the end that you don't want to keep it up, you should be able to sell the bike on for essentially the same price you paid for it.