How so? You haggle with people for so long, and you get better at it.
"But you don't actually haggle!"
No, there's no button for it anymore, but an imagination is a wonderful thing.
Because your enemies are not based on your speech skill..They are leveled strictly for combat.
Also i hate having skills increased that i do not want to specifically use.I have to buy and sell things to get money in the game,the odd payment or gift not withstanding.So just by doing a natural activity it counts towards my next level,when what should be counting is the skills i activiley use.Now if there was a conversation option where you could ask for better prices and the merchant agreed..then your using Speech and should count towards a skill increase.