Not at all wanting to tell you what to do, but have you considered a Patreon?

I would be super keen if there were a custom monthly sticker tier!

I haven't but that might be a fun idea! I'll have to look into it!

Yeah!! I'm on someone else's Patreon right now for exactly the same thing! It's really really helpful as I can't always outlay cash for multiple stickers at once. The short bursts of payment every month are much more manageable, and I tend to stick around for longer, even paying slightly higher than if I just bought a bunch of stickers directly.

Food for thought!!