Well, Morello uses a Digitech WH-1, which is the original issue of the digitech whammy. Now discontinued, your best bet to get as close to his sound is the reissue version, Digitech WH-4, which is the same thing with a few alterations. Im not quite 100% certain if these are the changes, but from what Ive read, the reissue isnt true bypass like the original, and there are a few less harmonising options on the original. Tone wise, the wh-4 sucks more tone, and sounds abit more digital.
I have a wh-4, and dont have that many gripes with it. My main problem is the size of it, it takes up a large chunk of my pedal board, though its pretty unavoidable, so you learn to accept that. You also need to know your theory to be able to get the most of out the harmonising settings, such as 3rd up, 4th down, etc etc. Other than that, I like it!
Im not sure how much Wh-1s go for on ebay now, but Im presuming itll be alot (quite rare now). The Wh-4 is £120 new, which is alot of money to be dropping on 1 pedal, especially one that gets constantly nailed as a 1 trick pony. You could look into the digitech ex-7. As well as having most of the settings on the whammy that morello uses (+2 octaves, +1 octave, +1/-1 harmonising etc), it also has a flanger, which morello also uses (Killing in the name intro, guerilla radio). Its also got a few wahs settings as well (crybaby setting included, which is morellos wah), and tons of distortion settings, its basically Morello in one pedal! It goes for around £100 new, so its less than the wh-4, and has more features.
And on the Wah topic: Vox wahs ftw :P
