So what is the maximum on this investment?

The thing is you did not point out all the necessary pieces of information, why need to create a deal in PM even though you can make it transparent as possible by publishing here or the site of it as well (if any). Furthermore, you said that your revenues are from investment on a website, so which website are you talking about? Is it your website or someone else? This information was not clear at all, who know you going to use your customer funds to invest in ponzi site