they aren't cheap.. not sure what you are considering affordable? a 68-9 340 car is not going to be cheap for a done or mostly done car 20k +/- 5k range i'd say.
The car you're looking to "settle" on seems is nothing you were looking for, but is probably still in the 10k range. I hope if you go for it that you'll be happy with it.
The others (68-9 340-s cars) are out there you just have to take time and look and maybe look outside your area to purchase.