At that point you should already be able to but the silenced handgun and have some spare change (ideally just over 500 RU), if not then do a side-mission for the stalker you just saved. Go back to the camp you begin the game and sell the collected guns. Play the first mission (rescue a stalker from some raiders) and collect as many items as you can from the fallen. Hint: Easy way to get hold of a AKM-74/SU, a RGD-5 Grenade and 2 anti-radiation caps very close to the beginning of the game: Then type the following codes to unlock bonus game content. Go to your STALKER-folder in your start menu and select 'Unlock Code' (alternatively go to your installation directory and run setup-bp.exe).