I agree with Tony, your local market will drive more revenue. Also it depends on the packages that you have in place on that server too. If you have oversold packages, yeah you won't make much from that server.
It depends how many clients you get will. More clients mean more income...I earned roughly around 5-6k per month...And you have to make sure that your servers are reliable and service are good in order to keep customer.
Frankly speaking, I never earn money from hosting reselling, but the thing is that if you are really educated webmaster with extra-ordinary thoughts and innovative ideas, you may earn great sum of money from reselling.