Not just FT dogs. A hunt test pro would charge $650-800 a month. Add in cost of the pup,birds, shots, vet bills ,etc and a started dog can be almost as much. 18 month old pup has at least $10K into it.
As far as selling a "washout". Most will be more then what the " normal" HT person expects and do well for them. I personally make sure it goes to a home that will care for them first. Never have gotten even close to the dollars have in them.