We bought a Trail SL4 off Craigs List to tide us over until we can pick up another full suspension 29er. It was in nice shape and we enjoy riding it. However, I managed to bend the big ring last week. It still works, but obviously does not shift great. We have a long ride coming up at the end of Jan, and I'd like to replace it.

It's an 8 speed with a 42T 102mm 4 bolt ring. Can I use a 9 speed ring?
Any suggestions for one that would be durable and not too expensive? I
I hate to put too much into the bike as it will eventually be replaced.