There are a number of ways to get your poster printed, both on campus and off. It's a good idea to get your file to the printer a week in advance. Otherwise, you may have to pay a rush processing fee. Prices are usually based on a cost per square foot and range from $7 and up. Most print shops prefer that you submit either a PDF or JPEG. It's a good idea to call in advance.
Be sure to double check the requirements for your specific poster venue. Will there be display boards to which you tack your poster? If so, be sure to bring tacks! Will you need to put your poster on chip board or foam core to lean up against an easel or on a tabletop along a wall?