I do value my customer base!! 
In terms of performance, they are actually almost identical…. I have quite a collection (of course) and I still use an SC2.2 occasionally, the only real difference was that it was impossible to make the old 1.05 version sound bad…. There’s a little more range on the attack and release on the later ones, and you can mis-use them, but it’s difficult!
The very early ones are valuable now, but it’s more a scarcity value than performance.
As for finding one for £300, well I would be surprised, but you never know!
If you ever see a JoeMeek C2…. grab it! that was the ultimate compressor. It was a late version SC2.2 re-laid out to fit in a tiny half-rack case. They are really good and have all the sound of the early ones.