I agree with Bob. A custom sail from a major loft will be expensive. If you just want to play when the air is light, look at Rick's sails or used sails of the right dimensions. If you want to race, go to someone with Class experience and be prepared to spend some money.

Even if you decide to have a custom sail built, you might want to play with some sails on a day when it's too light to do anything else. You learn a lot. For example try attaching your jib to the end of the pole