I love my thunderbolt, shoots anything I shove down the barrel. You just have to polish the 209 plug so the primers come out. Many don't care for them ,but I sure do.
I've turned Down a 1000 bucks for mine a year or so ago. They are getting hard to find
Which caliber?
A .451 will bring a higher dollar value than a .504.
I have a .504 Umag with a laminate thumbhole stock. Probably worth 650.00 in the current market.
It is not for sale
Condition, condition, condition. The cleaner, and closer to factory stock the rifle is, the greater the value. A LNIB rifle on GB might go for 1200. The further from stock and/or dirtier the rifle, IMO as a shooter/collector the value decreases.