What are you looking for? StubHub and Craigslist have taken over the resale market. Brokers mostly deal with high end tickets for the super rich guy who wants four front row tickets to the Stones and calls them the day before the concert.
That being said, I've purchased from a couple brokers over the years, never had a problem, they're all business, certainly more reliable than Craigslist. But for that matter, the scalpers standing around outside the park are more reliable than Craigslist,