Could be a really good score at the right price. And I mean like less than $200 a piece. If you have to pay more than $600 for the package it would be worth your time to walk away. You will need to dump at least $200 just getting these ready to ride on the road again, and that isn't including any actual engine repair parts that may be needed. But they will all need new tires, cables, and the engines serviced. Probably new gaskets and seals at the minimum. If the Moby is seized, like you think, that is new piston rings at a minimum, a new top end at most. If they have been sitting as long as they look and have not been properly set to be stored, then the carbs may be junked from the old gas. Also the morini engine could need a full rebuild just to clean out the transmission really well.
Like I said, still could be a sweet score at the right price.