Example of a very cheap purchase (but I buy for myself, not to resell), is this painting for which the auctionneers (lot 396 here
http://www.sarachaga.com.ar/73.pdf ) couldn't decipher the signature, so they described it as "European school", with no reserve price
The artist is Gen Paul (French), paid 60 euros for it
(would sell for 3.000/4.000 euros in a French auction)
I should run an arts & antique business again, jaja (but tricky to export right now)