I have bought plenty of used boxes. Find out the history and why the beekeper is getting rid of them and you should be OK. I agree with VMMARTIN, you should be able to get it for .50 on the dollar or cheaper.
A good sniff test should let you know if they had AFB if the equipment don't smell like wax & bees, don't buy it. If you are in doubt, dont buy it. If you are unsure, but think it is OK, replace the comb with clean/new foundation.
Let me know where it is and I will go get it if the price is right.