KMS' Potential System different?

Neither. Most of the time in the KMS FM, the equips with awesome potential stats are usually being sold by people with a high degree of funding, as you can tell by looking at the things they sell. Equips with pretty average potential stats are pretty much sold by the middle class. And the lower class is pretty much screwed. This is pretty much what you're seeing in GMS right now.

The price of Cubes in KMS is also pretty much at the same ratio as in GMS. You can probably sell a godly item at around 300-500m, buy 100 or so Cubes at 4-5m each (my pricing may be off since I haven't been in Culverin's FM in a while). On the same note, you can sell a godly item in GMS at around 1-1.5b, yet still get 100 or so Cubes at 1.2k NX each.

I wish cubes would cost 4-5m each, but it all depends on nx:meso ratio so I don't think it will ever go below at least 10m a cube.
Is that how it's like in KMS perhaps? then it would mean that it's practically cheaper to get good items, right?
And on a side note, I still don't get how there are such a few really godly cubed items in GMS where there are millions of players; when in KMS there are much fewer but still you see so many godly stuff from there.