I've seen (and eaten) Black Thorn between 28 Rm/kilo an 48 RM/kilo, so it is about the same price as Longlaplae (150 baht/kilo - 300 baht/kilo) and Linlaplae (400 baht/kilo, but can sell for as high as 800 baht/kilo)
The Nonthaburi Ganyao is far, far more expensive than any other durian, except maybe the 1,000 baht/kilo durians being sold in Rayong.