Maybe in this economy. The Yamaha is reasonably priced, $1900 if it's all restored and in great condition is what they can go for, maybe down to $1500 would be better.
The Maico, the 84 isn't as popular but it's a great bike none the less and has the proper heat treatment on the gears. $2700 is a bit on the high side but worth it. I'd say $2000 to $2500 would be more reasonable for that particular year provided the engine is completely healthly.
Although I would say fair market would have the Yamaha at say $1200 and the Maico at like $1800. I'd pick up the maico for $1800, of course I am out of room on bikes.