The price recently went up. It now costs 7 to 10 dollars a month. Before it was 4 to 6 dollars.
Say you have 100 domains to renew each year and you join this club for $84 per year.
8.29 * 100 = $829 + $84 = 913 / 100 = $9.13 per domain
I think namesilo does renewals for $8.99. Not really worth joining the club unless you have over 120 domains.