Here's what I heard from some student workers:
"The cost depends on the
quality of carpet you pick and size. It’s also a little more if you have them
install it (i.e. carry it to your room and put it down). We are ballparking an
average of $150, but that’s only an estimated average."
It might be more expensive to purchase on the spot..... but will you really have room in your vehicle to bring it from home? :)