I am UK based and bought mine on eBay. The previous owner bought the frame and never got round to building it up. I am new to track so I don’t have much to compare it to, but I am loving it so far as my first bike.
I also saw some press photos of Caleb Ewan riding a Ridley Arena Alloy for the upcoming London Six Day series. Whether he ends up riding the alloy or the carbon version I don’t know.