The engine alone is worth more than the 9-10k offer from salvage. Some folks irresistible appetite for stealing something from somebody is of no tact.
Sounds like a fair offer from the salvage yard. You may be forgetting that these folks do salvage for a living. They purchase the airplane, move the airplane, disassemble the airplane, market the parts, and store everything until it sells. They pay income tax, property tax, mortgage or rent, employee wages, and insurance. They're not going to offer the same amount as some private individual who wants the stuff for himself. On the other hand, they make offers and complete deals quickly. Like cars, if you want as much value for your used vehicle as possible, don't trade it in at the dealer.