There was once this blurb on Assembler that suggested not even the HK bootleggers could make pirate N64 games profitably, so by extension it would seem unlikely that a homebrew hobbyist could manage it at a price people would be willing to pay. But that was a long time ago. Are pirate N64 games not so uncommon now?

I also have the impression that the N64 is sufficiently difficult to develop for that there hasn't been much homebrew produced for it either.