Just athought..
I've been looking through my old "Airgun Worlds" and I noticed that the price when new in the 80's doesn't always reflect how much they are worth now.
Let me explain, the really expensive stuff was FWB300-s ( about £300) & Air Arms Shamal (about £560) now they were over twice what an Omega (£120)was new & about four times a BSF underlever (£55) .
Now a nice Omega will be worth approx what a FWB300 is worth , A BSF is quite desirable & commands a decent price but a Shamal you would probably find hard to sell at any price, until someone invents "classic" field target!
"Putting a country take on things..."