I have been through a few pedals now.
I've had a standard Dunlop, the Dunlop Slash one and the Morley George Lynch Dragon (first series). Currently I have the Dunlop Zakk Wylde and the Dunlop Dimebag CFH.
Incidentally I am a huge fan of Michael Amott as well! Of those pedals I always felt the Morley got the closest, because it was less "in your face" and had this rather mild wah sound that Michael uses all the time. I didn't like its "feel" too much though, which is why I sold it. All the Dunlops I've used have their strong points: the Slash was best for low gain and clean wah, the Zakk works great with downtuning and sounds very fat, the CFH has a volume boost, is very versatile and can sound much brighter than many other wahs.
Of those wahs I think only the Zakk comes at 100£ or less (at GAK).