What type of frying pan does not warp?
You have to make sure to buy a heavy duty, preferrably professional grade pan.  Thick base.  Most important.   I have owned my pans for about five years, and nary a warp.  Completely flat.  I also have a glass top stove.   Note to the wise, do not use a dishwasher to clean good cookware.  Always clean pans, pots, knives, etc. by hand.

Any good restaurant supply house will have good quality non stick pans.  Also, I' m not sure where you live, but many large department stores (JC Penny in the States, the Bay here in Canada) have good quality wares.  Be aware, they do not come cheap, but they will not have to soon be replaced.