more gold. also you need up to trade skill 4, to take some deliver jobs.
there is a very simple equation, to find how many trade skill points you need for each level.
where level is the level you already have. example if you have trade level 3 and you want to know how many point to get to level 4, you simply type 3 x 3 x 3 x 300 = 8100 points. 