A business mentor is kind of an oxymoron. I find my best advice is from just creating a thread about a question/concern/curiosity that's been bothering me. I almost always get an answer that I'm looking for and there's usually someone else who had a similar, if not the same question.
If you want a personal business mentor for your industry perhaps you could check out the online SBA business coaches. Although be advised that most are not entrepreneurs, they usually are retired corporate workers and I haven't had much luck when I contacted them about a year ago.