What number is a waste of time? Yours could be $350 and below while mine is anything over $125. There's a guy on Epay with a circular saw priced at $1000 which is completely ridiculous, but obviously he believes it's made of gold. So one never actually knows where that line is. I don't put much value in a running engine because I can always rebuild it and get it running, while someone else may not have the skills to do that so running is the important thing.
Why not just say what you want for it and save everyone's time to begin with since you already know what you don't want to except?
Yes it's not very common but it's also not complete. It could be less likely to find those missing parts than it would be to find a complete machine.
Maybe ebay is the best way to determine it's value?