
You get a +% to your base stats and at each stage 3/6/9 an extra bonus.
Some weapons (Craftable) get 4 enchantable bonuses 3/5/7/9.
Base weapon bonuses are mostly random, and enchantable ones are always random.
Getting to +6 is pretty easy and cheap, but beyond that it's a huge money sink.
Enchanting and replacing broken crystals are this game's money sinks, but they don't take money out of the economy.
I'd say transporation (tele scrolls for 11k/ea, and ports to quests hubs are 7k-ish at 50 areas), green charms (17k/ea), and maybe white crystals (41k/ea for the lv48s) are the only things that take money out but they're not expansive at all.