Yes, the higher the player level, the better the quality. Respectively, the wealthier the city, the more money merchant will have to spare. But, you really DO want to invest into Trade skill, since it gives you great 'discounts' when upgraded to a medium-high level(5 or up). Charisma is a bit useless as an attribute, but it does have some nice skills attached to it, so...
(Also, and off-topic, sorry, Die Zwerge. Teehee, lovely! )
Trade skill is for getting better prices for things. It also makes selling jarids a lot more profitable! Even bent jarids sell for around 400 at 10 trade skill!