I wanted to rebuild my booster while replacing all the clutch hydraulics. I was able to find new aisin master and slave on Amazon and Ebay very cheaply, but not the booster. The new booster part number is 31440-60050 and the kit is 04318-60030 and are not available from Toyota in Japan or anywhere else that I could find. Aftermarket I found to be impossible. After talking with local shops, I ended up driving up to Upland (east of Los Angeles) to Karps Power Brake (specialists in brake booster rebuilds) and talking with Jeff. He rebuilt it and shipped it back. He charged $135 plus freight.
Karps Power Brake
66 N. Central Ave
Upland CA 91786
909 985-0800
Karps Power Brake
66 N. Central Ave
Upland CA 91786
909 985-0800