I don't know how much you need or how far you are willing to travel, but there is a marzipan "factory" on Washington Avenue in Bergenfield, NJ. They make all kinds of fancy marzipan and sell to others, like bakeries and specialty stores, but also sell some retail products in the small area at the front of the building.
I found the place compliments of a friend who needed "pounds" of marzipan for a holiday recipe. She called around and surfed the net and found this place; they were willing to sell bulk marzipan.
Don't know if they still do, but I can tell you that its really fresh stuff.
Perhaps they would be willing to ship if you purchased a significant quantity.
Odense is almost always the only brand you'll find in the stores. I've sometimes seen almond paste in the can, by Love'n Bake brand. Balducci's carries that brand in other nut pastes as well...like pistachio...yum (although it's green). But, surely, as a last resort, you can make your own if you have a food processor or blender. See recipe attached: