I say get a nice guesstimate about how long specific jobs would take, and make yourself a nice little list like that. Like OS install: $50; format:$20; OS+format=$60 [but you don't need to tell that to your customers, just make it seem as a discount or something ].

Then for stuff that you don't have on your list say you'll make a free estimate [phone only, unless you feel like driving around for nothing]. People can take it or leave it, but at least you can negociate some stuff. You don't want people scared off by prices, otherwise they won't even call. I have no clue how much an advertising campaign would cost you. I'm not sure if it's legal to go to people's houses and just leave a print-out of what you offer in their mailbox, or if you have to do it with the post office only. At least you could cover some areas like this, while things get started out and until you could afford a website or something.