If you go over the Peace Bridge, it is only 20-ish minutes. We fly out of Buffalo regularly now and love it. It's so easy, the airport is well-run, clean and the parking is terrific. We've never waited for a shuttle as they are constantly roaming the parking lots looking for people arriving. I'd recommend it if only for the savings - we are flying BUF-MCO in September for $360 return for all three of us!
We always cross at Fort Erie and I would say its closer to ten minutes than twenty.