I agree with Deebie on a piece if you can spare...
I also agree with Lucy. Winterberry Iris Gardens has a huge variety of rebloomers. It's their specialty. If they introduce something, it will most likely rebloom, but they also do Spring-bloomers as well.
I've had a good experience with Winterberry. They're kind and generous and their plants have been true to name and most have performed well. Two have even tried to send up bloom stalks, though they got frozen off. They were only planted four months!