l have an innovation which is covered by a provisional patent which I'd like to sell
Typically, no one buys provisional patents unless they are really beyond amazing. most aggregators purchase issued patents or portfolios of applications. Most companies license issued patents. I know it is not what you want to hear, but it is essentially true.
That said, if you do your research, you can identify those companies that may be willing to pay for your patent pending idea and you may be able to negotiate an exit or a royalty deal, depending on the value of said idea.
