The key to a healthy sandbed is infauna not the sand. So I would suggest you go to www.ipsf.com and check out what they have. I would suggest things like their...
Reefworms
Mama Mia worms (aka spaghetti woms)
ministars
bristleworms
sandbed clams

They are expensive though so you might see if you can get some of those things from maast members.