Not sure if you guys have ironed out exactly what your subscription system will be like but I had an idea that I thought I would atleast share.
You probably already have the standard sub cost to be considered a subscriber. For argument sake we'll say $15 since that is kind of the industry standard AFAIK.
My idea is to allow a type-in recurring sub amount. Based on the amount, you would get x subscription perks. So, if someone can't/doesn't want to do $15 a month, they'll buy the game and likely never sub. However, if you give them the option to subscribe at $5, or even $1, a month, once they reach the $15 threshold then they get 1 month of subscription benefits. So, a $5 subscriber would get the subscription benefits on their 3rd month subscribing since they reached $15 total. Then it would restart, 2 more months (month 4 and 5) would be without subscription and then the 3rd month they'd get another sub month. I think you could so the same if they want to subscribe at more than $15/month. So at $30, they'd get sub x2 perks a months. At $20 they'd get a sub x2 perk every 3 months.
This seems like a possible way to make sure you don't lose out on any potential sub revenue from those that can't meet the minimum sub fee ($15) every month but are willing to do less and get the sub perk once every few months.
Literally just a random thought I had. I'm sure there might be some issues or downsides but I haven't had the time to flesh it out completely...just thought I'd throw this out there.
Compulsively clicking the refresh button until the next update.