I took some time to add the following popup to my sites just to see what people will write.
The following I had popup when someone exited the join page without joining.
http://www.badtushy.com/surv1ey.aspx
almost all had the same concerns
Recurring billing (some had other things to say but over 90% said recurring billing)
So I did two things and it helped me generate more signups.
1) on the join page I added a link saying you can cancel by clicking here, it takes less then 30 seconds.
2) I added a one time signup option (it's $99 for 6 months) and many chose that option.
Figured some here might find this helpful