So you still haven't decided if you need one? I would like to find some non-superstar, since superstars usually don't have the interest of mentoring people. Superstars are easiest to find though, their work puts them all over the internet if they are popular. I think the only way to be mentored by a superstar is to collaborate with them on a popular (their) open source project. I would like to find someone with the same interests as me and who is more experienced, but they are harder to find since they are not considered "experts" yet.