I don't think you're being silly at all. 1 rovert. I think it's a lovely thing to do.
I had one of my dogs cremated a couple of years ago and I think it was about �40 (for that, I got his ashes back in a nice urn, with a card and a little spray of dried flowers). Your vet will know how much the local pet crematoriums charge. I hope your little cat can have a good quality of life for her remaining time, but when the end comes, just remember, you're doing the right thing by her and not letting her suffer. K xxx