Gilbert H Wild (www.gilberthwild.com) is having an end of season peony sale, looks like all are on sale, a lot at $7.50 each. Also if you buy 12 you get free shipping and 10% off, use coupon code UP.
I have had a lot of success with the peonies I've bought from them, they do have a reputation for sending the wrong plant, though. I ordered all of my corals from them and they were correctly marked. I do think I have some pinks and whites that aren't correct but my labels faded so much I can't be sure. I'd suggest you label any that you get from them and check the flower against the peony database to confirm as they do guarantee the correct plant. I've never tried them on it--I used them a lot when I first started collecting peonies and didn't even realize they might not be what I ordered!
I ordered/received 15 from them in spring and have another 10 or so on order for fall, these will be marked (spring ones already are!) and I'll be calling them on their guarantee if I get other than what I ordered! Their roots are usually large enough to bloom the following spring after planting so you won't have long to wait to confirm.....
If anyone is collecting yellows they have Nova at $7.50, I ordered 2 for fall.....