I believe these use the HP 56 / 57 cartridges or the design is identicle. You will probably find that there is a slight difference in the molding in the cap so that one doesnt fit in the other (same as Dell Branded Lexmark).
The Rimage website specifically says that this printer will cost you the most to run because its the budget printer and will cost $0.30 per disc.
Anyway, these cartridges are easy to refill if not allowed to run empty, you can just peirce the sticker on top, inject till ink comes out and then suck 1-2ml back out.