Aside from buying mats and pulling the occasional melee earring that has patk/crit, there's not much else in the game that you can buy with mentos (grasslands, etc aside since those costs are insignificant). Would be nice to be able to buy other consumables like phoenix redemptions, angel sighs, phirius pots, golden repair hammers directly from mems, instead of having to farm mirror world etc for them. (I'm not sure if mirrorworld was meant to be a fun activity, but if it was, the devs failed rather miserably on that.)