I picked up a Ibanez Prestige RGT3020 at a pawn shop in Reno a few years back for $300 out the door. It was dirty as hell, but after some thorough cleaning and a good setup it's one of my best guitars.
You can do it with just about any delay pedal. Just turn the feedback all the way up, hit the 12th note harmonic on the low E, then step on the pedal, turn down the guitar volume, and turn the delay time slowly until it goes down an octave.
PRS does this as a standard service through their tech center. Kind of pricey, but they include the cost of the trem and it's a full on factory job:
http://www.prsguitars.com/ptc/
I love mine. Super easy to program, effects sound great, built like a tank. Particularly when you factor in the prices they're going for these days, it's a great option for an all-in-one unit.
My only criticism is that the pitch shifter can be a bit dodgy at times.
Bonamassa still has one in his live rig as well. I've always thought it's a solid amp if you dig the Marshall tone. Really comes into its own if you can pair it with Greenbacks and crank it up to stage volume.
I'm using the standard, had an OS as well but I thought it was a bit too boomy on the bottom end. I loaded both with Lynchbacks though - people seem to like the OS better with V30's.
The only 2x12 I've found that gives me the depth of sound I'm used to getting from a 4x12 is the Port City Wave. Still not the same but it's way easier to lug around.
Other trick I used to use when I thought the sound guy would complain was to start off with the amp cranked louder than I really wanted, so when they asked me to turn down, I could comply and still be around where I wanted to be.
There are a lot of pedals out there that really sound amazing, but I've never been able to get used to playing gain pedals instead of amps. The feel just isn't there IMO. You can certainly get by with gain boxes in a pinch, but if you're used to playing tube heads, pedals just don't measure up.
I think the BE100 is the most versatile of the three. You can definitely dial the sizzle in, particularly on the BE channel, but it also has the ability to go very high gain with HBE and has a fantastic clean as well. Haven't played the Metroplex though. The Helios sounds awesome but has a very...