STALKER Clear Sky
This mod lets you buy for free, the flash drives for upgrading weapons and armour from a trader. You can buy the flash drives from the traders.
A flash drive mod, get them at the start of a new game off the Clear Sky trader. Gives you 10,000 RU to start off with as well.
This is a relatively simple mod that enhances the function of the various consumables in S.T.A.L.K.E.R.: Clear Sky.