Well, the printer is free, but the ink will cost you.
From what I have read, Lexmark has one of the highests costs per printed page. So, the cheap printer ends up costing you more over time.
The first question to ask before using refill kits, or off-brand cartridges, is what is the cost of a new print head.
If the lexmark is like HP's, then each cartridge has it's own print head, and you can try any and all options without any real risk. I have seen many a print head ruined by the useof refill kits, and off-brand cartridges.
That said, I have started using refill kits and off-brand cartridges in my Canon 7000. It has just become to dificult to find OEM ink for this printer.
My refill and off-brand cartridges come from Tyler Martin Company www.tylermartin.com
I have been happy with both the quality of the inks, and their service.
Other options, are to search the surplus sellers for ink cartridges.
Try www.compgeeks.com
and www.pcliquidator.com
Chas