I have experienced great relief from pressure sores & sitting discomfort by using an alternating pressure cushion *under* my Stimulite. (about $150 from http://www.flowcushion.com/flow/)
I have NO financial interest in this company.
OK... For all those Purists:
This is NOT a Medical Device. It probably has not been studied on people with paralysis. It may not have been shown to be any more effective in prevention of pressure sores in those with paralysis than placebos. Send flames to /dev/null
A reasonably handy person can tap into the electrical system of most power chairs to install a 12 volt cigarette lighter.