They must have someone there at the feed store that harvests them, then. It's not a situation where they're resold, like I was thinking you meant. Pardon my ignorance.
I sure hope that last vet will see Harvey. Otherwise, I'd say start searching the next town, and the next. If nothing else, you could at LEAST potentially find out whether he has some form of gigantism (sp?) that's causing the problems. I know what it does in humans - it definitely shortens their lives.
Edited to add:
I understand the monetary difficulty. When we had to put our LGD down due to metastatic cancer, it ended up costing us over $250 just for the medicine to put him down, and the cremation, all after the exam and xrays and sucnh - and that was with US taking his poor, dead body down to the town where they did the cremation, ourselves.