Hi,
I bought my .177 about 2 years ago and paid £225.00 it was in almost mint condition..However before that I bought a much knocked about .22 for £90.00 and restored to near new condition even down to a BSA Re-Blue and Service at the Factory..Last year I saw one for Sale at Bisley for £375.00 ...This might give you a rough idea...
Regard's
Inproved