I don't know about the Quad Cities, but if you are going anywhere near Cedar Rapids, there's a store there called Fittings Unlimited that has a good selection and knowledgeable staff who can help you get a proper fit. Here's their info:
402 10TH ST SE
CEDAR RAPIDS, IA 52403
They specialize in prosthetics for mastectomy, but don't let that scare you away!