Personally, I think that the gambling box should not have escalating prices, but to balance that, make the box have lower rates and qualities, but add more leveling tiers of gambling boxes.
I wanted the gambling box to be a fun thing to do on the side, that's why the items in it aren't really good (or the loot table), and yes, a different gambling box will be for each phase with tools of this phase, so the escalating price is there more to limit the "gambling only" potential meta
