Appreciate that hosting isn't free, but having some sort of $0 plan would greatly drive adoption, at fairly little cost. I personally would be unlikely to launch a product that cost me a monthly fee just to run, even with zero paying users. Once I have paying users, I become a lot more willing to pay you. You could consider something like the following plan: Testing. $0/mo, 50 users, no support.

It'll be more effective marketing than anything else you could reasonably buy, and unless you have serious architectural/scaling issues shouldn't be too expensive for you.