Stay away from the Custom Classic AC30s, poor build quality and reliability on those things.
The reissue AC30 is a great amp - you can have chimey clean/crunch out of the top boost channel or alternatively slam a treble-booster pedal into the normal channel for some Brian May esque tones (yum).
One thing though, you really need to get the model with the blues for the best AC30 tone (imo). The other alternative is to stick some G12H-30s in there but don't use Greenbacks in an open cab (flubby bass) - I don't care for the reissue GB's in general.
As for an original, you should easily pick one up for under a grand. What you need to ensure is that it's not been ragged all over the place - the heat in an AC30 chassis means that some old ones have the wax dripping out of the transformers (not good).
Another route is to buy an oldie in need of repair and buy some repro transformers - I did this and used OEI iron, that was an AWESOME AC30 and just loved fuzz pedals (esp Big Muffs, yum!)
:twisted: :twisted: