With a background deep in marketing and graphic design, I was....skeptical....of on line printing companies. I am not going to do a blanket endorsement of the industry, but will share that co-workers at one of my freelance gigs shared Vista Print with me and I am a convert. I have ordered business cards, post cards, invitations and brochures for three companies from Vista Print , including a set of brochures featuring photographs of reproduction paintings at high quality. The level of customization of standard designs is amazing -- Vista also offers the ability to upload a design of your own. I have been outrageously pleased with the product for the price, although I would tell you that the quality falls just a bit short of top quality and there is not a wide range of paper stocks.
Note: They run CONSTANT deals -- if you don't see a deal on the product you're looking at on their site, do a quick Google search and you'll find one.