Congrats. As a big fan (and owner) of Gryphon for a number of years now, i look forward to your impressions.
1. i cannot speak to the street prices of these...but happy to check. i will PM you if i find anything.
2. I have only compared Antileon regular to Colosseum. Overall, the Antileon was the first to make 'magic' the tubes do (for me)...and yet have the most insanely propulsive and powerful/controlled/disciplined bass i have ever encountered. The upper mids/treble were rich with detail but dark...not cloudy at all, just like you took the orchestra...and asked the piccolo players and move their chairs 5 rows back behind other players who play more bass or mid-heavy instruments.
You should find that there is an intensity of sweetness in the mids which can be addictive...really addictive because it has little grain and is exceedingly clear, no fuzz or loss of detail at any volume i care to play.
The Colosseum came along and clearly descends from the same lineage (ie, voice)...but it is more grainless by a good margin, and maintains the bass power...but its upper mid/treble range has suddenly asked the piccolo players to come back 5 rows again. So the balance seems 'right' to me...and yet it is grainless, pure, extended and effortless all the way to soaring highs.
HOWEVER, could I argue that maybe [just maybe] the intense tonal sweetness in the mids is diminished a hair? Like from 100% to 98%? I think i could make that case...it was certainly my observation when moving the Antileon out of my system and putting the Colosseum in. (i am told the Mephisto puts that right back in...and also has other advances across the board.)
The only other thing i would say is that i NEVER would have felt the need to go to Colosseum, except that my 14-yr old Gryphon had a finicky little resistor problem that took 5 tries to find, and when they eventually found it, someone made an offer i could not resist...and a Colosseum 2nd hand came up at almost identically the same time...so i went for it. I have no regrets, but i was perfectly happy with the Antileon sound.
hope that helps...