I would use Adenium_Ko or Orient Adeniums (Rinoa) for obesum seeds. Both have eBay or their own sites.
http://orient-adenium.wix.com/...
Kukuan ( Adeniumcenter ) on eBay is very trustworthy and has a wonderful selection of Obesum and Arabicum seed.
I have received seeds from all of them and very good germination.
Rick
