What's the minimum level for..

Cash bags?

Imma start playing in Khaini for proper today, and I need monies.

Most likely the same level as you need to be to buy all other NX stuff, which doesn't require any level if I recall correctly. If Nx does require a level it usually mentions that in the description.
Other then that they usually never give it a too high level requirement, so you should absolutely be fine after level 16 which shouldn't take longer then a day.

Edit: Actually, I recall seeing a notice about a certain CashShop item that required level 30+ but I'm not sure if it was the Cash bag or the Master Key...

Final Edit: Checked again and it's on their site. Level 30+ can buy Master Keys.

my level 7 noob cant buy it so im guessing its like those store permits and such where you need to be level 16

prob either 10,15,or 20.

But do buddy me.

I think it's 15 but I'm not 100% sure tho...

I'm level 15 at the moment, and can't buy.

Must be level 16+ like SMegas.