There is hand-quilting thread which is different than machine thread. Gutterman thread is my choice for machine piecing and hand-quilting. Joann.com frequently has sales of 40 or 50% off their threads and also, coupons you can use on-line for regular-priced items that are not on sale. There are TONS of on-line quilting shops available. If you plan to hand-quilt, make sure the thread says for hand quilting, as it has a different finish on it and a bit firmer.
I have also heard good things about Connecting Threads, but haven't tried them.