Original 5G at a guess - earlier than mine due to colour of the grips. if you look at the back on the "photo" side it will give 4 digits This is Month and Year. Depending on condition £40 - £90 in full working order with no replacement parts needed or faults
Oh bugger - just re-read. In .22 That knocks it down a bit as they are beginners ie cheap 10m target pistols and you cant use .22
Do you have all the interchangable foresights? Unscrew the shroud at the front ant the "element" A pressed steel sight bit - will come out. Should be 5 with the pistol IIRC
Late 70s at a guess as all the ones I ve seen are