i never had a colonic, but instead bought a colema board (not as good as a colonic). i am happy that i did it, so i can use it before and after my liver cleanses. i bought a folding one, because of storage. but based on your colonic prices i will have earned it back in 2 1/2 times and if you buy a non-folding one, it will cost you less than 2 colonics.
check out also the colonics forum. good luck and save some money.