You are fantastic, my friend. :)
I'll be talking about this situation more and hopefully something can be done. What is the USD amount you need per month to keep this running and give you a nice payment for your time and efforts? Is it $7,000 a month? You mentioned 100 users and 10 SBD (at $7), so $7k seems a bit high to me. If you were assuming a $1 SBD, that's different and would put us closer to $1,000 a month.
Are you hard-pressed to make a decision here immediately? If so, I may consider just donating some of my witness funds to keep you going for another month until something more sustainable can be figured out. I'd really like to see a pay-per-use model. If someone is using this data a ton, they should pay for that. I run a handful of queries once a month, so it's not really worth $70 a month to me. Maybe for others, it is.
The problem it seems you're running into is the tragedy of the commons. You gave something away for free so that everyone thought they could use and abuse it. If they had ownership in it or they had to pay, maybe they'd respect it more? Have you considered creating a token for access on BitShares much like the BUILDTEAM token? People would have to send you a certain amount of the token to get access that month and you'd sell the token on the open market to cover your expenses. You could even do a staking think like the build team is, if you wanted to get really fancy. That way people who use the system more than others could easily pay in more usage tokens than others. Does that sound interesting at all?
When I mentioned this to some others, they seemed to think, "Meh, I'll use MongoDB" which discouraged me a bit. I'd like for there to be multiple options out there for everyone to use.
Maybe we could hop on a call or a chat sometime to work out some details of how we can make this profitable for you and beneficial for the community.
RE: SteemSQL is moving to a monthly subscription model