In a good market that car could possibly go for 25k. It probably cost that or more to build. But the market for buggys right now is so soft I personaly would start by offering 16k and go to 20k tops IF it didn't have any obvious repairs and was not jerry rigged in any way. I sat and waited on a buggy for sale for about 4 months before I made an offer just recently and got a 75k buggy for 50k.
That car looks pretty cool and would be a perfect desert car with that beam front end.
Good Luck!