New freewheels are available; Nashbar usually carries several with different cogsets. You will likely need to go to a shop to have the old one removed; they all seem to require different tools and can be a bear to remove. Last time I had it done they only charged me 5 bucks.

However...Highly unusual for these rear cogs to become bent or warped; they are very durable. By design, some teeth are angled slightly to facilitate shifting. Are you sure this isn't what you're seeing?
Another thing...A common problem with freewheel rear ends is bent axles. The axle bearings are much farther inboard as compared to a modern freehub, and often smaller in diameter as well. Might as well check that while you're at it.