These old pistols are becoming much harder to come by. 3 years ago I bought one on the other forum boxed (1923 vintage)and virtually mint for £100 It had been on there for days with no interest. They are splendid little guns to shoot although many people do struggle to cock them. The only fault is the very small grips but it would now take a bit of money for me to part with mine.

I also bought a prewar Senior boxed (slant grips and mint) that had sat for days with no interest on the for sale section for a similar price. Lately even tatty unboxed Seniors can go for up to £100

I sold a boxed prewar slant grip .177 Mk 1 on here very recently that was in very good condition with all patent stampings etc for £130 but regretted it almost immediately
You may come across a prewar example at the next arms fair at the Motor Cycle Museum next week
If you are a member of a shooting club then it pays to let members know that you are interested in these old pistols. I was offered and bought a very tatty post war Mk1 Webley for £25 and then several months later a nice prewar one with no rust or pitting for £20. It needed a new piston head, breech seal and 1 grip but most spares are readily available and don't cost too much
Good luck with your search
John