Larry,
You will want to find out the exact model and report back - late-70's with a ‘B2600’ model might be a grey market tractor. You'll want to know the deal on grey market machines before buying one, kind of a 'buyer beware' deal, but they can work for some people. To make a long story short, grey market tractors are machines built for use in foreign countries, and imported into the US. Currently, import of such machines is banned, due to the lack of safety features. However, some machines can be retrofitted with the proper guards, ROPS, and other equipment to be 'US Spec' for safety. Keep in mind that even so, on some models the PTO rotates the opposite direction of US models, and running a US implement on such a PTO might cause early failure.
Also, parts may be impossible to get, since not all grey market tractors have a US equivalent model, and even if they do, there is a chance you could run into problems getting a specific part. Also, some dealers are more cooperative about doing service on grey market tractors than other.
Well, that's a bit more than you might need to know, since the machine might not be a grey market.
Sounds like it might be in the $3,000-$3,500 range, without seeing it or knowing many details. If it is a grey market, that price minus costs for US safety equipment and a set of books for the US equivalent, if there is one.
I hope this helps,