As part of a house purchase? Make your offer on the house assuming you'll need to buy a new dryer, and this one is total junque that will need to be hauled away. It adds negative value in the current state. That should be a relatively small part of any house purchase price, anyway.
Without actually replacing the belt and verifying correct operation, there's no way to know if something else has broken, too.
The fact that the seller didn't do that could mean they don't want to bother, and could also mean they actually know something else is wrong with it, since they are not repairing the belt and taking it with them. If it actually works with only a new belt, good, you come out a bit ahead. If not, you won't lose any value if you don't pay more for the house on the basis that all the dryer needs is a belt.
Incidentally, if you end up with house and dryer, go ahead and replace the rollers while you are far enough in to replace the belt. Taking it far enough apart to replace the belt (and then putting it back together) is the big pain, the rollers often wear out, and sometimes you can get a deal on belt, rollers, and belt tensioner for little more than each part alone. Also clean the ducts!
Hmm. "Ventilation ducts are available it’s just not Hooked up to it." Suggests a possible need to verify (don't trust, just verify - caveat emptor) that those ducts are correctly and safely configured, in addition to any issues of the dryer itself.