Need Design work for Letterhead, Flyer For Computer Repair S

I need a letterhead and flyer created for my computer repair services company. I am not sure as to what information I should put on it. My company repairs and upgrade hardware and software, remove viruses and spyware, setup wired/wireless networks, etc. I have some ideas of what to put but not much to catch the attention of my potential customers, which means I would need someone whole already has expertise in creating such documents for my field. My company is Rocket City Computers LLC and website address is http://rocketcitycomputers.com. I am on a tight budget for now and can only afford work between $20 to $40 bucks. I will need to be able to add and remove stuff on it so it needs to be in MS Word and PDF formats. I am looking for someone I can build a relationship so they could do more work for me in the near future.