I haven't used either of these, but have heard great things about both. The first is Bullseye Turning Supply, Kate Harrow is the owner and a member here on IAP.
At Bullseye Turning Supply, we have the juice to stabilize all of your wood! At Bullseye we are equipped to vacuum stabilize your wood pieces and blanks. This process can take punky, fragile woods and make them much more dense and solid for turning, carving, or machining. Stabilizing also helps...