you dont need much BUSB I dont think.... I seem to be getting by on very little. Not quite sure of the ins and outs, but if youre only putting yours coins in the Den then you only need a tiny bit for paying the fees. If you feel a bit more ambitious and you want to do the farming, you have to buy an equal amount of BNB or BUSB to your coin so that theres equal liquidity in the pool. Ive tested that out in a small way with the DEC farm but Im thinking of investing a little bit more to put some Eth in a farm as well. Its keeping me entertained at the moment thats for sure!