Not to sound like a lawyer here Mutt but....it depends. On what? Traffic, promotion, how hard you work the site, etc.
But let's say you have a good paysite, as you described, and have your traffic ducks in a row. I break it down to a daily or weekly number. For me the goal is always 5 sales to start but I am a small company so perhaps someone else's goal would be much more.
It also depends on the type of membership you offer. I do one-time only Memberships as well as rebills but if you did JUST rebills then by year's end the rebills would be much higher (perhaps the chargebacks would be, too).
But in the end it really comes down to how much traffic you can get and your conversion rate. Five sales a day - or twenty or more - might be shitty if you're throwing tens of thousands of hits to it. But five sales a day might be wonderful if you're throwing 2K hits.
So yeah, got lawyer up here and say it really does depend.
