Poster printing gets very busy at certain times of the year (AGU, etc.) and scheduling can be crucial in being able to use the campus low cost services. Pro tip: finish your poster early!
Earth Science has an HP Designjet z5200 in Webb Hall 1015. USB printing at $2 per foot, prints to 42" wide semi gloss HP paper or standard white paper. Email proposals@ (suffix with eri.ucsb.edu) for a recharge code. For scheduling poster printing, contact Peter Green, pfgreen@ (suffix with geol.ucsb.edu).
Poster printing is also available at ITST: www.itst.ucsb.edu/computing.html
Another option, not on campus, but worth checking out if you would like to avoid traveling with a poster tube, is to have your poster printed on fabric: fabricposterprinting