Thanks for all the advice. In the end i managed to pick up a Kowa 773 20-60x in really good condition for under a £1000. I think that it'll do 95% of what i need, without breaking the bank. I've used it quite a lot later and the improvement over my old scope is remarkable. I think i will probably end up getting a Kowa 883 in a few years, but for now i'm more than happy, and the Kowa iPhone attachment has made getting photos for IDs much much easier.