I'd say you could easily put up $30 an hour... or double the first price! o_o;;

I go by an hourly rate, set at an average of how most commissions take me to produce. I also factor in how much time I have per month to create said commissions vs. what I need to pay my bills. I try to fiddle that # into 'an agreeable price' considering most artists I see on this site vastly under charge (and therefore undermine for others) a living wage. $30 an hour is far more professional, industry, price and no doubt you deserve it - but if you need the $, well I have found I have to bargain down a bit to continue to bring in steady work (which I need).

Try testing the waters with an increase and see what happens (though I say for about a month minimum, one round is too subject to other factors). That's really the best way to see if you can ask more and still receive an income.

If you're doing this full time and need to make a full time living wage, then you'll need to price yourself the same way any other contractor/consultant prices themselves:

Take a reasonable hourly wage for a full time worker in your industry working at a company and multiply it by 4-5x. That's how much you charge for your nose-to-the-grindstone time actually working for your customer.

The reason you need to charge this much is because, as a general rule, you'll be spending about 3/4 of your working time not actually "working" in a billable sense (and then you get to pile expenses on top of that). There's all kinds of overhead that sucks up your time and you need to account for that or you'll just end up poor, frustrated and overworked wondering why you can't keep your head above water charging what seems like a perfectly decent hourly rate.