That shouldn't be a problem, if you have names in Hitfarm you'll be earning that in a week anyway, for some in a day.
Hitfarm is very selective though and extremely hard to get in since they're targeting big portfolio owners (with lots of traffic), but if you have a name that is already making a large amount money elsewhere and has very good traffic, they'll be willing to consider you.
$500 a month isn't going to cut it though, they'll want your portfolio (that you will move over them) to be already earning over 10K a month on other PPC providers in addition to at least 5K/day uniques.