Well...the mistake was in the setup. You need to do this proper CL style. First you offer the seller of 50% of asking. Then when the seller is totally offended, you counter with 75% of asking. Then you never respond to any more communication. Ugh...CL buyers.
Wow.....$20-$50k to do an engine rebuild/swap! Since the Tiger camper body is a single unit piece it can be unbolted from the chassis and reinstalled on a new truck.....So, you could probably buy a heck of a truck and install the camper body for less then a rebuild!