I hosted my crimefest site on https://www.clever-cloud.com/en/ since they gave every new FREE registration 20€ worth of credits to run on cloud based webservers which could easily serve my website for over than 1500 concurrent visitors (at the Saturday we broke Crime.net)
however, they don't host SQL Server in their Data Center, but from third parties which lead to painfully slow SQL Connections
You should check out clever cloud ( https://www.clever-cloud.com/en/). I haven't used it myself but a friend of mine is quite convinced about it. I think you can set a price limit on how much you want to spend and then the platform scales accordingly until your limit is reached. Again, I have not used it myself so no guarantees but I hear good things.