Kelli,
Locally (Philadelphia Suburbs) I can buy rebuilt 80s with new VIPs and Hydros and rebuilt vavlve for $100.00 but the shipping would break the deal for you. You might check around to see if a local dive shop in your area has any deals.
Sadly in most cases an old tank is worth more in aluminum scrap. Buy the time you buy an ebay tank pay fro shipping and have it rebuilt, you can get a new tank.