I think it's weapons, armor and accessories. Each number represting the amout of different kinds that are obtainable for that place.

For example: Icicle Inn has 650 then you might have to separate the digits: 6 - 5 - 0 , then maybe the 6 represents weapons, 5 armors, and 0 accesories. Not sure it's right, and have no idea which number represents what if it is right.

Anyway that's my guess!