Another source to mention is FX Sails.
Sunfish Sails, Catalina Sails, Spinnakers, Hobie Sails, Small Boat Sails from the Sail Store
Just be warned, they get mixed reviews.
I have heard very good things about the quality and the price for new sails usually can not be beat. I have sailed on a boat that uses these sails and for the normal recreational boater, the quality is very good.
The negatives have always been poor delivery time. If you want them new for Spring you should be ok.
Thier on line quote request is very fast and easy.