First - the people on $3 /mo shared hosting are not in the target market for this service. If you are on shared hosting, you don't need loadtesting.
Second - I think subscription is fine. As a subscription, I recognize that I -should be- load testing on a regular basis. As a-la-carte, I am much more likely to say "umpteen dollars?I can do my own loadtest for cheaper then that."
I'll second that. For personal use it may seem like a lot of money, but for the target groups that needs this kind of service it's cheap. It's not just about the cost of servers, it's much more the time spent doing it.
First - the people on $3 /mo shared hosting are not in the target market for this service. If you are on shared hosting, you don't need loadtesting.
Second - I think subscription is fine. As a subscription, I recognize that I -should be- load testing on a regular basis. As a-la-carte, I am much more likely to say "umpteen dollars?I can do my own loadtest for cheaper then that."