Hi chipdeals,
While the forum is mostly for consumer information rather than wholesale information … there is a list of mattress manufacturers and retailers in the Los Angeles area here and it may be worth calling some of them to see if they can supply you with what you need.
I would start with Flexus Comfort (on top of the list) who is a member here (meaning I think they are among the best in the country) and also sell mattresses wholesale.
Phoenix