Klehms and Adelmans both have nice sized 3-7 eye divisions from my experience. Klehm's is really good if you like the "cactus dahlia" style blooms; quite a few of them were hybridized by Klehm. Both are pretty good about leaving big enough feeder roots to support the number of eyes on their divisions. The biggest divisions I've seen so far have been from Fina and some of the ones from Select Plus. I say some because I ordered several Itohs from SP, most of which were huge, probably 10-15 eyes each. There was only a single one that was around 6-7 eyes which was actually the size I was expecting from all of them. All of the ones I've ever ordered from one of the larger mail order places have been bareroot when delivered in the fall. Hillside offers small species peonies in 4" pots but that's the only one I can think of that isn't bareroot in the fall.
How small are you talking about with dwarf? I know Klehm's has an area on their website for rock garden peonies, I think that's as small as they get. Some of them are 12" or so tall and have smaller roots. A lot of those are fernleafs and fernleaf hybrids.
Brooks Gardens has about the same sized roots as Klehm's and Adelman's and their prices are great this year. I also like A&D and Hollingsworth--same sized roots as Klehm's and Adelman's and they generally include a bonus peony if you order several; don't know what the cut off is! I ordered enough from Hollingsworth last year that they included a free Garden Treasure Itoh; 1st Itoh that I've ever received free, and it was pretty big.
