Hey,
Copylite sells the reset chips for all IU's for $15.50 outright.For folks in the northeast you can send your chips to copierchip.com and he'll reset your chips and ship them back to you free of charge for $12.50 each you can normally get 2x's the life out of these units w/no Issues. I know the guy copierchip.com he's an absolute genius (we worked y=together for a couple years).
CopierChip.com he'll treat you right he also does it for the C250/252/300/352 and the c451/550/651. Hope this helps !