That's easily fixable, and an experienced brass musical instrument technician sees a lot of them like that.

Whether it's cost effective depends on the horn.

I'd guess it will cost $200 to $400 to repair and look like new.

You can get a Chinese import for $150 and they play reasonably well.

A Bach Stradivarius costs $2500 and up.

This is one repair that you can't do yourself. Well, you could, but you're going to mess up the first 50 or so learning.