Not enough!
You asked an open ended question. The answer is how hard do you wanna work. There are studios making over $500,000 per year but realistically speaking it really depends on how much you wanna work and how good your work is. With good business practices and quality you can make some pretty good money. Part time vs Full time, specializing, African, there is too much open to answer that.
Well put nctaxi. Everyone is different and the biggest variablesare 'how hard do you want to work' and 'if you do good work'. If you work hard and do good work...then you can do well. Although if you work hard and put out $hitty work...well then your burning your bridges and it will catch up with you eventually. By all means, don't expect to work 30 hours a week and bring in six figures..