Delon Wright from Utah 100%. Top 5 talent that might not get picked top 20. Has tons of room to add to his frame. One of the best defensive PGs in recent draft history. He can also score. Why he's not getting more love is a mystery to me.
Does Willie Cauley-Stein count? Not really a sleeper.
I also like the Pettaway suggestion that HamGlaze made.
What about that forward from Nebraska Terran Petteway? He might be worth a shot.