I havent raised barter at all (cha 4) but still I can buy stuff for such cheap amounts (stim 30 , ammo 1 max 3, ...) and sell with a great profit margin (10mm smg fetched 1200). I arrived with 30k caps at vegas and left with even more

make those barter points count, low barter and every merchant tries to screw you

http://www.gamesas.com/index.php?/topic/1131332-relz-welcome-to-bartertown/