Price definitely should be mandatory. 9 out of 10 times I see something I'm interested in that has no price I will pass it up without a second glance. On the 1 out 10 (or less) times that I do inquire about a 'no price' item I quickly find out why there was no price. Somebody trying to get rich.
Why would you want to waste your, as stated earlier, valuable time fielding phone calls and emails from people that are never going to buy your product? And only because they want to know how much it is. I prefer to list my price as well as all the info I can think of so that if I do get a bite there's a good chance I can reel it in and close the deal. If everything's there for them to read they have no other reason to make contact other than to make the purchase. Or at least that's the goal.
As for shipping 'labor' I respectfully disagree. I do some Ebay selling sometimes. When I list something I package it for shipping first, weigh it on my scales, and get exact pricing from USPS. When the sale is done I purchase postage online which also grants me free delivery confirmation and I schedule the postal employee (online as well) to pick up my package which is also free. Even if it's a large package I simply enter the pick-up location as "at the front door" and they still have to drive the extra 200 yards down my driveway and get it for free. So to say you have to go here and go there and it's worth something really isn't necessary IMO it just makes you somewhat inefficient. Not being disrespectful or throwing off on anyone, just some constructive criticism.
The classified ad section on this site is a SUUUPEEERB idea and need. It just has the potential to be so much better. If it worked well there would be little need to do Ebay with most military parts as these are generally the folks buying the stuff. Unless you want full retail, cuz we're definately wholesale buyers.