Other than this is there anyone else who has the artwork for sale?
It sounds crude to ask but I've never used Scott before and it's been my past experience with people handling MAME related items (trying to do non MAME stuff) that the artwork is typically sub par from the original.
It's the only place I have seen, but I happen to know that Kalan shipped some NOS hypersports artwork to mamemarquees for them to scan so I imagine their artwork for the hypersports sideart is pretty decent.