In writing an answer for How do experts make dovetails by hand that fit so well?How do experts make dovetails by hand that fit so well?, I realized that there is much more to say than "get a good saw." I have some old saws that I am trying to refurbish, but also just purchased a Veritas Dovetail saw ($60), which is performing so much better than the box store models. While shopping for this saw I also found Rob Cosman's $250 saw.
While some of the cost differences between these saws may simply be marketing, I know that a number of design features contribute to a superior saw. So what makes a great saw great?