What I do is build my poster on the computer to fit an eleven by seventeen piece of paper. Then I convert it to a PDF file and save it, (always open it in Adobe Acrobat to double check the look and colors and save it again) I move the file onto a flash card or burn it onto a cd. I take the cd or flash card to Kinko's (copy store - should be everywhere) where they have work station computers and printers for you to use. Where I go they rent the computers by the hour but you pay by the minute with a credit card. Before I do anything I make sure the color printers are avaiable and loaded with the right paper and that no one else is gonna be printing anytime soon - THEN I start up the computer, insert my credit card and open up my pdf file of the poster. I send it to the printer. Once it confirms the charge to print and begins the upload I close down my workstation and go wait at the printer for the poster. The reason I do all this is to keep the number of minutes that I use their machine to a minimum - they are charging my card by the minute. I can often get my 11 by 17 print for a few dollars that way. They have printers capable of printing larger but these are not self service so you will have to pay and the last time I used them it cost about the same as what you were quoted.