Do not change your gear every time you level. The actual bonuses to gear come each few levels, if you are spending 10-20K on a piece of gear every level, you'll get nowhere in your objectives to make Diablo 3 gold. Instead, you should stick it out with what you have got if you can. This gets far more tricky in the later difficulties in the game, but even in hell difficulty you may grind in this way.
Do anything you can to prevent buying gear as an alternative every level. Classes that use a non-weapon offhand possess a little advantage in that weapons and can not roll Diablo 3 gold find and magic find when Shields, Mojos, Sources, and Quivers can. Most of the time, a new weapon changes everything. The states on weapons typically make the biggest jumps from level to level so that ought to be the very first place you look.