I know someone in Colorado on another forum - they say they can get good genetics locally.

I take that to mean that some of the headshops there sell seeds, but don't know for sure. I'd see where dispensaries that sell finished product might not want to also sell seeds - it would kind of be a conflict of interest.

Why not check out some websites for Colorado breeders & see where they sell seeds?
Almost every breeder who's big enough to have a website has a vendor page.

I know Reserva Privada has a Colorado division, but their website says they only sell to MMJ patients through the dispensaries - maybe they've expanded that rule since recreational use is now legal?