HEY - anyone remember that bloke who came to fix the ice box in the fridge? You know - the one who fitted the tesseract beerfinder! I'm sure he said something about a transmutation gubbins as an optional extra. If you are going to need so much cash, it might be worth the investment to convert some lead to gold!
Go for the ReverseBarleycorn model.
[John Barleycorn, John Barleycorn
makes a man into an ass.
He turns your gold to silver,
And your silver into brass]

Or maybe you could find that Potter kid you barred for being underage a couple of years back. He may still have that Philosophers' Stone he was trying to flog for a pint of Riggwelter!

Quack!
GtD.