I thought you would be able to get the seals from Suzuki in Australia as OEM items. I've been able to get seals for RM250A, RM125S and RM125C from Suzuki.
Bearings as already mentioned can be sourced from most of the bearing suppliers, but stay away from the 'el-cheapo' budget priced made in China bearings, go for the more reputable brands such as NSK, Nachi, Toyo etc.
The only bearing I'm not sure on is the left hand drive shaft bearing found in the above mentioned motors, the one with the location pin in the outer race. Although it's a standard size and readilly available from the bearing shops, I'm not sure on whether it's best to stay with the pinned version. My thoughts on why Suzuki added the pin was to stop any chance of the outer case rotating in the housing particually because when hot and under max load that shaft cops a lot of work. Any other opinions would be helpful on this subject.