I have been getting mine from Lone Star and Balsa USA. If you have deep pockets and only need A little most LHS carry Mid West and I have found A lot of it to be very hard. Like Stick said, old kits are A really good source. I have A couple of old SIG kits that have balsa that is hard to cut with A hobby saw!!! You never said how much you need but I try to keep A good supply so I place A an order from Lone Star and stock pile it.