I had to buy several new pans when I got a glass top, because a lot of mine had deformed in the heat over the years and had curved bottoms. They were good quality pans too - it just happens.
Pans are something I think you mostly get what you pay for, so if you cook a lot be prepared to spend a lot. If you hardly ever cook, you should hardly spend anything. I really enjoy cooking so I buy pans one at a time so I can get nice ones without breaking the bank. My collection is mostly Calphalon and All-Clad but I'll buy any brand that seems sturdy and well-made. They don't match but they're all very functional!
(I don't use non-stick so I don't have any specific recommendations, sorry!)