Would never suggest any such thing, bose -x
But the end result is just the same as far as the price you paid - somebody sold the stuff without knowing what it was worth.
Deicing fluid suitable for aircraft (the issue is more aluminium corrosion in inaccessible cavities, than paint coming off, BTW) is always expensive, and I am sure that if the pricing was bogus the airlines would do something about it. It costs a huge amount of $$$ to spray an airliner which got covered in ice while parked.
Schools I trained at used car antifreeze. Should be safe on paint but not so sure about aluminium.
I flog all my old stuff on Ebay too.