I just replaced the booster on my 86 Turbo. it was almost impossible to find, so I had it rebuilt here:
http://www.pwrbrake.com/
Fortunately, they are about 45 minutes from me. I drove it down and waited for them to do it-about 1 hour. The good news? $130.00!
It took about 45 minutes to an hour to replace the booster-if you're handy, you can do it yourself!
Also, make sure you make sure the check valve in the vacuum line is working properly. I ended up replacing mine. It was about $30.00 from Toyota.
Hope this is helpful.