Everything here in Japan is expensive. I tried to video tape alot of the games here but the stores would not allow me to. Sorry. Some games I saw such as Super Dodge Ball (US), Metal Slug X (US), Ultimate 11 (JP) were like 800,00 Yen and up. So if you are buying from individuals who have the games, you might get them cheaper. One of the main retro game stores in Aikhabara (I don't know if I spelled that correctly) is called "Trader." It has a ton of retro stuff if anyone decides to visit Japan. I'm leaving Tokyo as we speak and heading back to Osaka. Hopefully I can find something there.
Now let's not forget, these games were in stores on the shelves. Getting the game from someone who already owns it may come cheaper. But it also depends if they reference the price guide on the site. Now I'm not trying to stir up anything, but like some, I would like to see the guide updated if the site reference other sites such as ebay, on market prices or what the games are going for now. I know it's hard to do that because some individuals post there items for different prices and the rarity or scarce of some games.
One Super Potato has a super famicon dodge ball gold cartridge for $10,000.00 USD, that is 1000000 Yen with some type of clear casing. It was just beautiful but expensive. Other neo geo games I saw such as Rage of the Dragons was like 780,00 yen. So if you're coming to Japan to buy neo geo games look forward to spend some doa. Other than that just ask people on this site for it, and get it cheaper. Hope this helps. I didn't really see any MVS carts at all.
I only meant that the price guide on this site is considered bias because it's outdated, since prices have changed and some games trade hands for significant amounts of doa. If you would like to reference the price guide by all means do not let me stop you. I'm going to try sneak my camera in this time and not ask so I can post substantial information for ya.
For those who were able to provide me the games I was looking for thanks.