Yeah, was just going to say this is Planet Fitness' whole value prop .. Cheap enough that the lie you tell yourself that you will go more next month is easily worth $10 / month.
Their cheapest plan is something like $12.99 and with fees it's up to $18 or so. And that was 5 years ago.
Aside, is Planet Fitness still unfriendly to people that push themselves during workouts? I'm no bodybuilder and never will be (my little-girl wrists made that decision) but the idea of a "lunk alarm" was rather off-putting.