I"ve gotten spoiled by cheap machines. But if that Dressmaker was complete and worked properly I wouldn't worry too much about the price.
Fixing them can be expensive as grandmahoney said, but so is fixing a modern plastic wonder machine. Ever had to replace a computer panel in one? Eeeekkkkk!!!!
I'd try to negotiate it down, but in the end .... I'd probably buy it. Remember, they don't make good machines any more.
Joe