I've had great experiences with pawn shops in this area. They have nice selections of decent bikes at good prices. They do not sell stolen goods. I bought my favorite bike at a pawn shop for $100. It had obviously never been ridden, and went for about $450 in the LBS.

OP--if you don't know much about bikes, it might be best to stick with well known mass market brands, such as Trek, Giant, Specialized and a few others. Look for bikes that are in new or excellent condition. Check all components, tires, wheels, bottom brackets, head sets, frames and forks. Take it for a test ride (very important). Make sure it fits and feels comfortable (most important). Ask the sales person if they can do a little better on the price and they often will, especially in the winter season. Good luck!