It is smart to evaluate your position with this. My first bike was $300 wayy back when. After I found I enjoyed riding, the parts swapping began. Geeze, sounds just like car stuff. All schooling and you'll pick it up fast enough. You already have your MTB riding experience.
BikesDirect certainly sells a lot and they participate on several forums. They do offer a good value in the usual generic Chinese made frames with quality components. I was looking at the entry level offerings since you began this discussion. I'd say go for it either from them or used.
are there hills where you live?? if not get a fixed gear.. cost you around 350 for a decent one,, and you will get a really really good workout!! I have more fun on my fixed gear,, than on a road bike,,and they hold its value really well
__________________ I know you're not standing on your front porch with a bag of money waiting for me to call you. But I'm not some 18-year-old selling a cure for AIDS. I'm 46 years old, I have 22 years market experience, I know this business. So pick up your skirt, grab your stones, and lets go make some money