The above poster was spot-on about buying better bikes from a good shop. You don't have to spend 3000 on two high-end Treks, but you should plan on spending at least 300 to 400 per bike in order to get something of minimum quality.
And don't forget that you can, in fact, buy used bikes through Craig's List, EBay, and so on, that are still in great shape. So as the above poster said, go to a good local bike store and chat up the salesman. Take a look at some more expensive bikes and see if you can buy a pre-owned version if that interests you.
Also, don't forget that you'll be spending a little extra money on gear as well. You'll need decent helmets (50 bucks and up each), gloves (15 bucks), water bottles (6 bucks) and, if you really get into the sport, shoes, shorts, etc.
Cycling ain't cheap, but it's easily the greatest damn sport in the world.