Certified GKH Gardening Expert
We don't recommend certain brands or products but a quick search of the Internet for reputable seed companies didn't find any either. They are easy to divide or take cuttings. Seeds need a cold period, plus they can take up to a year to germinate I've read! I would advise against buying them from individuals advertising on selling sites. A lot of people report scams.
Here is a link to planting bleeding heart seeds: