Why?
I'm not going to mince words here your cartridges are expensive and all you have to do is post the rom file.
If you're going to stick to this path I will find an alternative elsewhere.
Because after all this work, there are constantly people trying to resell my content by passing it off as their own, at least this way they have it less easy.
However, if you search on Etsy you will find that the price is perfectly average, in fact many cost A LOT more. I also do time-based special pricing on the Etsy store.
That said, everyone is free to make their own considerations and look for alternatives.