Aardvark

$500 is pretty bare bones entry level. Buying off C.list, Ebay, etc is dodgy unless you know that the bike really fits you. This is near impossible to determine on older bikes bc your local shop won't have them in stock. I've used http://www.bikesdirect.com in the past. They are a TX b&m that set up an online shop to import recent designs under new names. You're basically getting a free frame and paying wholesale for the components. Beware, though, they have no customer service after a sale. To determine if a bike is going to work for you, you have to go test ride a bunch of bikes locally, study your fav bike's geometry online, and then look for a geometry match on bikesdirect. ....or you can just guess.

I've got no affilitation w/ BD. Good luck! .matthew

In all honesty, a decent road bike is going to cost 1k, at least a new one would. I started riding last year and they told me off the bat "you're going to want the better bike now." And i didn't listen when I purchased initially so I ended up spending more dough for an upgrade. If you're not worried about brand, this is a pretty good deal: http://www.performancebike.com/bikes/Product_10052_10551_1073180_-1_20000__61000