You may want to purchase the prism for the 35 bucks and later upgrade to a better skimmer.
I have a CPR Bak Pak 2R which I like alot. Along with the pre-skimmer box, it works very effeciently, but like phases99 said, the box does take up valuable real estate. (although it does hide that nasty pump and the tubes and wires.)
I ultimatly chose it over the remora because the remora uses a waterfall style return and I felt a return tube would ultimately be quiter. The only problem is that they are about 100 bucks more than what you would be paying for your friends old skimmer.