$500 wont get you a new bike that is anywhere close to that nice. $500 for a used bike at a bike shop wont get you much around here either.

modern bikes are stiffer and lighter. that said, the bike in question should be reasonably light and extremely durable.

if you are looking to race go modern. if you are looking for a comfortable, reliable, and reasonably priced ride follow your current path.

edit:
i wouldnt call it an amazing deal but i think it is reasonably priced if you dont plan to change much. adding drop bars wouldnt cost much but adding sti levers would bring you out of what i would call reasonable.