For those who have not printed their posters yet, you may find the following info helpful...
Use the LEFT HP PS3 plotter in TBH 20, not the right one. At least yesterday, the right one seemed to have some type of backup/error, but the left one printed my poster right away. It is also easier if you save a PDF of your poster, and then when you print it, make sure you have the box called "print actual PDF size" (or whatever it is called) checked, not the one for 8.5x11. It should cost between $10 and $14 depending on what paper type you choose.
I got my poster laminated at FedEx Office for about $35 (!), which I thought was a bit excessive but it was my fault for not asking how much it would cost before I had them do it.
I bought my foam board at Michael's for about $10, but the only problem is that the largest size they have is 30x20 inches, so you will have to buy 2 and tape them together. This should probably work though as long as you are careful about transporting it.