If it is circa 1980, there will be no servo motor, or speed control dial, only a clutch motor. The clutch motor's speed is dependent on how much or little you push the foot treadle. The 206 is an O.K. machine, $800 is a bit pricey but not totally unreasonable, especially if it has reverse and comes with extra feet and other accessories. If it was only used very little, the chances of there being anything wrong with it are very small. If you buy it, take it to an industrial sewing machine mechanic and have them set the tensions, set the timing, and look for worn or broken parts. It will be the best $100 to $150 you will ever spend. Also, don't trust any thread that comes with it, use old thread for practice only.
BTW, if the machine head is in storage, all you need to do is put it back into the table (connected to two hinges at the back of the bed of the motor) connect the machine to the motor with the belt, plug it in, and it will be ready to go. Have them thread the machine for you if it isn't already threaded. Standard thread is size 69, 138 is twice as thick and is not used for most sewing.
No one lives forever, the trick is creating something that will.