I have four Neo Geo Fusion converters available, after I made one for myself. The PCBs were fabbed with ENIG finish, Gold fingers, bevelled edge, etc. so they're the best quality and each one has been tested in my AES and confirmed to work with a handful of MVS cartridges.
£50 each, plus postage, (the two cartridge connectors and to a lesser degree the PCB options are most of the cost here)
I can also 3D print the shell for a bit extra if you want.
£50 each, plus postage, (the two cartridge connectors and to a lesser degree the PCB options are most of the cost here)
I can also 3D print the shell for a bit extra if you want.