In my opinion there is really no such thing as an independent distributor. He may sell several different lines but he is still trying to get your business and may not be giving you a totally accurate appraisal of the job and chances of success. I find it hard to believe he could give you a realistic quote without the water and power on. Even a quote with the power and water on might not be totally accurate. There are many problems that may not show up until the work actually begins.
You need to find a consultant that only consults for a better opinion on the deal. You need to get the whole picture including what it will cost to get it going again, the earning potential of the wash and advise on how to get it going.
I have known of no deal that went well with a wash that was not in working condition without turning on the water and power. If the bank refuses to do so I would offer them the value of the land and no more.
The quote you got for $150,000 sounds high but without testing the equipment there is no way to know if it is or not. If he is an independent he might have to charge more for parts that he has to get from a manufacturer for existing equipment. Have you talked to the distributor that installed or maintained the wash when it was open?
Bottom line, I would be very careful on this one. Starting up a non-operating wash can get really expensive and time consuming especially if you have no experience with it and can do none of the work yourself. To put it in the words of another poster you may hit a home run but you might also strike out. Make sure you know what you are getting into.