OEM wheels will always be cheaper 2nd hand then aftermarket merely because all our cars came standard with them and there are more in circulation. OEM 18in wheels from 335i's with runflat tires mounted would go for the 700-1000 range on E90Post depending on condition. Hell, even 219M's with Michelins of an M3 would be in the 1400 range. Those were easily $3k or more brand new from the dealer.