Below are several reliable online sources for purchasing poinsettia seeds.
Heirloom Non-GMO Red Poinsettia Flower Seeds for Planting – High Germination Organic Garden Seeds for Classic Holiday Blooms, 100 pcs where to buy poinsettia seeds
When searching, be aware that many retailers sell "Summer Poinsettia" seeds. These are actually Amaranthus tricolor , a completely different plant that is much easier to grow from seed than the traditional holiday variety. Go to product viewer dialog for this item. Below are several reliable online sources for purchasing
Sells Deep Red Poinsettia Seeds in various quantities, including 100-piece packs for $16.99 and bulk 500-piece packs for roughly $60. 100 pcs When searching
Offers both Red Poinsettia Seeds (around $17 for 25+ seeds) and premium high-volume organic packs. Organicindiaseeds also carries a premium 1000-piece pack for approximately $90.