I don't mean to criticize the makers of the MVS price guide or the guide itself, its quite comprehensive and obviously a lot of work went into it, which is very cool.
BUT... I have *always* been of the opinion that an MVS price guide is unnecessary. MVS cart pricing doesn't even closely resemble that of home carts and CDs. In other words, MVS carts aren't quite as "collectible" as home carts. What I mean by this is this. Just about every single MVS cart (with a handful of exceptions) follow a VERY predictable pricing model - their value is directly related to the money that game could make sitting in an arcade machine. There are TONS of MVS carts in existence, and games that no longer are viable in the arcade are worthless to arcade ops who therefore sell them at whatever they feel. Most Neo games aren't realistically profitable anymore and just fall anywhere between the $20-$100 price range, depending on the attitude of the seller (the arcade market determines MVS prices, not collectors).
Like I said, there are a few exceptions (fight fever, Super dodge ball, futsal, brikinger) but for the most part, this is how the MVS market behaves.
John