Not to further confuse matters but most of the Amish in the Finger Lakes region are actually Mennonite. I think you will find these links very helpful:
http://www.lake2lakequiltguild.com/py_sewing.htm
http://www.lake2lakequiltguild.com/links.htm
Be forewarned, most of these shops you will drive right by and not even realize they are a shop. Very little signage and a few don't even appear to be businesses from looking at the road. However the area is beautiful and very scenic.
Additionally at the Southern end of Keuka Lake in Hammondsport is a delightful shop that specializes in Asian prints. They are not Mennonite though so the prices are on par with most LQS in the $9 per yard and up price range. They are called Lake Country Patchwork. If you like Asians don't pass this one up.
Hammondsport is absolutely the cutest little town. With some nice cafes and antique shops as well as several B&B type places to stay. Definitely worth the stop and only about a half hour very scenic drive from Penn Yann. You can find lodging in either Penn Yan or Hammondsport. Or you can opt to stay in Geneva which is right on Seneca lake with loads of hotels.
Edited to add, some of the mennonite shops do not accept credit cards. Cash or check only but I think check would need to be drawn on a US Bank so bring cash for shopping. I know Edgewood takes cc but Golden Lane does not.