at underground in the student centre, how much is the cost to print a large poster?? does anyone know prices./

Pricing depends on what you mean by "large poster." What dimension are you looking at? Is it in colour or black and white? Is it on regular paper or cardstock? How many posters do you need printed You can find there price list here: http://www.msumcmaster.ca/underground/priceList.htm
If you can't find what your looking for there you can go in or call them for a more specific quote