The Mk2 is a popular choice among Airsporter fans, some believing it is the best of the Airsporters. (I don't - I believe the Mk1 is)
Prices can vary for all the usual reasons.
A trader or dealer price is usually the top value.
A private sale will usually be less, depending upon how much the seller is prepared to (or needs to) accept.
Condition is all important with those with the Airsporter marking etched into the air cylinder and low use, fetching the best prices.
I have seen Mk2s advertised for as cheaply as £50 or for as much as £300+.
Anything approaching 'mint' condition -
Trader/Dealer - £300+.
Private seller - £200 - £250?
I am not an 'expert', I just love these old Airsporters.
Good luck with your valuation/sale.
No doubt others will be along to add to this, as well as those that claim to have sold their mint example for £60.
ASM