You could always use the stronger Pound vs Polish Zloty (as its not as strong vs $ or Euro). Currently You would get about 5-5.20PLN for a £1. Look at Allegro.pl (which is bigger and more popular in Poland than eBay) and You see that for about 180PLN posted Youll get a XT cassette – so about £35-40 and You should be able to get them to be sent to UK for not much more. £23 saving from RRP. (XT chainsets are still for about £100 on there as well)
Thats only if You really want a XT cassette and dont want to spend a fortune. Or a UK option: I bought a new Deore cassette for my constantly skint mate, get them on eBay for £11, sram 7.0 or 5.0 chain from JeJames and Youve got Your cheap but working really well winter transmission to trash and not feel sorry.
I had a Deore and a LX cassettes and TBH I couldnt see or feel a big difference. Lasted for almost as long – but Lx was 1/3 more expensive.