Attached Link: http://www.kinkos.com/our_services/store_services/signs_banners.php#order_info5

As a former Kinkoid, I can tell you a little about their capabilities. A 2x3 poster on matte paper will run you right around $40. You'll need to make sure you render at a pretty high resolution to get good results. 150dpi at 100% should be adequate. If you save it as a single-image PDF you might save yourself a $10 RIP fee (Raster Image Processing). Most service bureaus will charge at least twice that - at least they used to - but there may be someone around ding it for cheaper these days.