Hi-I am hoping someone can help determine a fair market price for a 3phase converter. It was my dads and I know nothing about these. I have someone interested but they are wanting me to give them a price first. It is an Arco “c” model roti-phase and let’s assume it is in good pre-owned condition with little use. 230v, 15HP/45HP max. I have researched and seen these from $649 on up for a used one? This was on eBay. It seemed pretty high to me, maybe not? I am just wanting to give this guy a decent fair price and get this out of the garage, lol. I apologize if I have posted this in the wrong forum. Thanks for any help!