I'm gonna take a wild guess and say you're out on the peninsula... to be honest when you said ya got 6' diameter trees my first thought was no f'n way... anyway most of the logging I do I don't get paid until it goes to the mill and the landowner don't get paid either, just how I do business... wish the mill would pay before maybe then I could afford fuel... its unlikely as Hel that the mills will pay a lump sum for an unknown quantity of wood, and even more unlikely that they are going to pay before it crosses their gate, the mills are cagier then the loggers (and that's say'n somethin).
If the loggers are going to give you 40% then that's a pretty good deal, there is a bunch of work involved in getting wood out of the woods, and it involves some pretty big and expensive machines. When its all over and the smoke has cleared the logger will probably make about as much as you or less (most likely less). If the ground yer on is fairly flat, as in no Sherpas or balay lines to walk the property line, their biggest danger is going to be those windfall pick up sticks logs, Bucking big wood like that is always fun but throw in the up in the air and who knows where its going once its free and its very possible some one is going to the hospital.
It been many years since I have had any kind of involvement with shake blocks but my understanding is they buck into rounds and split on site then stack em on flat bed trucks to take em to the mill, if'n that's still the case then you really want someone else to do the work for you, cutting blocks takes a darn good saw hand, and splitting em is brutal back braking work,
There are mills/brokers that take ceder in the Puget Sound area it just might cost an arm and yer first born to truck them out there,
If you really want to get more money sit on em until the housing market and economy picks back up a little bit, Best of luck to ya though.