Hiring trainers is a great gold sink and I think it works from an RP perspective, as in order to learn to improve a skill, it makes sense that hiring a master trainer would be costly.
At least every couple of skill levels, I try to pay a trainer. Also, I tend to collect some jewelry and dragonbones without hauling it around to merchants to sell. As a result, even without any economy mods, I'm usually broke, and I've only managed to save up enough to buy a house during one playthrough.