Price varies wildly according to condition and other factors, like how hard they are to find in your area, color of the machine, age, etc. I paid $135 for mine which is in good condition (maybe excellent too but there's some dings in the bed). Some have paid as little as $10 or $25 or even gotten them for free and some have gone up to 3 or 4 hundred bucks.
So it depends. :p