Six years ago my two cost me £50 each when I got them from Cats Protection. I believe the fee has gone up since then. But they did come to me wormed, flea'd, neutered, microchipped, vaccinated, insured for three months and with a thorough medical check (the younger one was thought to have a heart murmur and thus be entitled to free veterinary treatment for that condition, but none of his subsequent checks have shown it).
I've had my money's worth several times over, even accounting for broken glasses and crockery and one of them having pee'd on my best pure wool jumper thus ruining it permanently.