Buy it on the cheap, say $200 to $500 depending condition, what's there or not, trailer etc. then pull the MPEM and send it off to have a DESS lanyard programmed to it. Get it back and go from there.. A vendor called Westsidepowersports online is reasonable and has a quick turn around. As an option, Westside only needs the MPEM, they'll sell you a new lanyard and program it.
No matter what the seller tells you, if at a minimum you can't hear it start and run, it's a dead ski and not worth much. Many have been screwed over with the all it needs is a $50 part line, don't fall for it, assume everything is bad if it doesn't run.