Bartering isn't really worth the points. It doesn't actually change the buy/sale price by 10% per level as advertised. It actually changes the buy/sell penalty by an amount. Doesn't appear to even by 10% either.
For instance, an elemental essence buys for 550 gold (intedimensional trader with 100 attitude) at 0 bartering. At 5 bartering, that price is down to 425. At 7 (the max I can get with gear) it goes down to 375. It's a pretty consistant 25g less per level. In 7 ranks the price has decreased 33%, no where close to the advertised 70.
Selling the item is less consistent. it's 114 at 0, 119 at 1, 125 at 2, 147 at 5, 156 at 6, and 167 at 7. I can't really make any sense out of the progression, but at 7 ranks it's increased by 46% and not the 70% advertised.
If you have to sell a LOT of junk, maxing out bartering can help. My recommendation again is to use the respec Demon when you have an inventory full and then go visit every shop in the world for selling and buying. Don't let it stop you from buying the stuff you see when you see it though.
As for pickpocketing again, it seems to be a one-time deal for each NPC, so just wait till hunters edge and then go pickpocket every shopkeeper in the game for either a stack of gold or whatever item looks useful. Gold is more efficient than selling back items, but if it's something you want to buy anyway it's better to pickpocket that than gold.
Last edited by Sotanaht; 05/11/15 12:27 PM.