I dunno what is going on with this forum but I posted a reply this morning only to see that it is missing. I also have way more than 6 posts. Anyway here are prices I've seen in the wild for what you need. You will need only one I/O. depending on which route you want to go (JVS or JAMMA).
01. Capcom Vs SNK 2 GD-ROM $50.00-$75.00
02. NAOMI I Motherboard $60.00-$100.00
03. JVS I/O $40.00-$145.00
04. Sega JAMMA I/O $50.00-$145.00
05. Capcom JAMMA I/O $150.00-$275.00
06. Sega Power Supply $45.00-$125.00
07. GD-ROM Drive $100.00-$278.00
08. Dimm Board (Non Net) $90.00-$120.00
09. Dimm Board (Net Dimm) $127.00-$250.00
10. SCSI GD-ROM Cable $30.00-$35.00
11. GD-ROM Power Cable $30.00-$45.00
12. Sound Amp (If Needed) $22.00-$35.00
If I may be of anymore assistance let me know. These are prices for things that I have personally have run across in my NAOMI collecting journey. Hopefully you'll get to see this reply before it vanishes again.