What I think is interesting with SA is the fact that you (theoretically) pay a one-time cost. How can a one-time lump of $10 cover a running one? If nobody would get banned, things wouldn't work (a user is bound to consumed more than $10 over a period of time). New members won't help, they'll also require bandwidth.
This pretty much means that either:
A) They have to be happy with the banhammer.
B) They can cover their costs with advertising.
In either case I'm not spending ten american moneys.