Interesting, but the amount is so low
I was hoping for someone to swoop in and permanently buy out my sig space.
You have a low amount of posts and activity. You are not really trusted here, so why would anyone pay for your permanent signature???
You can leave the forum tomorrow, or just remove the signature at anytime. It is safer for them to buy it monthly, with checking that you keep the signature and are still active.
You will find noone to buy definitely your signature before a couple of years I guess.