I am 5 carts away from a complete MVS collection. All of the ones I'm missing are common carts.
For the last three years, I have almost daily checked online to find carts to complete my collection. So in other words, I have been actively collecting for that entire time and I will share with you the least common carts I have run across.
Bear in mind, this doesn't mean that my list is the end all be all of rare carts, just what I have found being active in the market over a long period of time.
Ragnagard (believe it or not) - I've only run across one, and I bought it.
Pochi & Nyaa - I've only seen one, and I bought it.
Pleasuregoal - Found one about 8 months ago and bought it. Another one recently came up.
Sengoku 2 - I have seen three total in as many years.
Twinkle Star Sprites - I have seen two but they sold before I could get to them. A friend of mine gave me his which is how I got mine.
Matrimelee - I have only seen 2 in three years. Lots of boots out there though.
Bang Bead - have seen 2 in three years.
Here are some carts considered rare which don't seem all that rare to me;
SSVS - I have seen many of these
Puzzle de Pon/R - Again, lots of these
Neo Mr. Do - Have seen about six of these in three years.
Nightmare in the Dark - Plenty out there.
Pop N' Bounce - Seems more common than a lot of common carts.
Hope this helps.
Yes snk definately priced themselves out, at age 12 I had enough cash to buy the AES when it came out but could just about manage one game
A 12 year old had $700 in 1990?
Jesus.