I've had a few scopes, and if I were in your shoes I would buy a Hogster 35mm, to scan with, then get a good 4-6X NV scope,( I prefer 6X) the real ones, not electronic. I think they hold zero much better.
Best way to do it on a budget, IME. If you can find a used FLIR 536 ( 2700 range) they have issues but hold zero well, IME. Cheaper thermals suck at being able to have pinpoint accuracy, I'd much rather use a good NV scope.
Cheaper thermals are great for detection, but I wouldn't want to have to shoot with one.