You buy l2coins with nscoins or adena, before the packages are opened l2coins are treadable, once opened they can not be traded.
1000 Lcoins cost 250 Nscoins
8000 Lcoins cost 2000 Nscoins
The package you want to get with the +7 weapon b grade and the +4 c grade armor and some extra potions exp boost k.a you can get it directly with nscoins, it makes exactly the same money.