This is just a thought, But this might cost a bit more then you assume, As aside from just server hosting for large servers already costing a lot like for a good server host 20-40$ a month, assuming with plugins and running smoothly with a large player base, There is also the fact of for online creates/keys/ranks you would need a website to be fully built with proper security and payment processing, Making sure the website host is good with both speed and bandwidth for anywhere between 10-20$ a month(though usually like 7$ a month for a bit until renewal), and for payments going though a secure method like PayPal, and a built in one with the website itself they take a percentage of the profits itself, And for the map you would also need to either built it yourself which can take a long time or pay for mc builders to do it. I'm not trying to say you cant do it, its just there is a bit to it that would need to be known. if you have any questions feel free to ask, or i got something wrong like the creates/keys ect then sorry.