Money is a one of the factors in buying a vette , what is more important is the quality of the car you get for the money you will part with. And what you want to do with the car when you get it .
If you but one for less than 25k or there abouts you will be working on if for quite some time and will,most likely spend 10 to 20k on it or more .
Having said that I have seen cars that have asking prices of 40/45k and higher that would need 20to 30k to get up to a reasonable condition.
When you find one you like , or think you like , get some one who knows their vettes to look at it with you.
Bfit
This is worth a look at. Although it's not a roadster
http://nswcorvettes.com.au/forum/index.php/topic,11399.0.htmregistered , has been in the club for years ,