Hm, looking at the Toner selector at Office Depot, they have cartridges for the Dell 3100cn, which, if similarity in model numbers means anything, would probably work on the 3130cn. So maybe sourcing the cartridges would be easier than I thought.

And the compatibility notes for the cartridges list only Dell printers period, not any other brand.

So maybe Dell really is making color laser printers these days. That would surprise me, but it's not outside the realm of possibility.