Back of napkin est.It has been stated that the units are leased & suggested $8,000/mo + a royalty on volume each unit produces. It is also been stated that each order requires a 50% non-refundable deposit(again for each order)4 units = $300,000 or 75,000/unit or $37,500(financed) to be paid off(with in first 5mo in operation)from leasing revenue + volume royalty. Yes there’s a volume royalty to be conservative not considered here. After the first 5 mo.& for the remainder of the first yr 7mo x $8,000=$56,000/unit(again not counting royalties)Reoccoring annual leasing/unit/year=$96,000/yr

Perhaps a royalty rate of $1.00-$3.00/gal which would be competive.

Customers advantage = expenditure accounting, set alerts for ordering salt
Pctl advantage=monetary info always available for each unit, receives signal if unit fails thus ability to quickly react to repair/replacement

Hope DE / Gary sees this suggestion.