It was indeed on eBay. Unfortunately the detailed listing no longer appears as it is literally 90 days since purchase. Yes unfortunately that's how long it took to ship from US to UK, send to AFA for grading and authentication and then send back to the UK again.
The inner saber was only visible in the 2nd picture but only in the top of the arm slot as it was fully retracted. The listing title and description gave no mention of telescoping saber. It literally just said "w-lightsaber".
I can't have been the only one that spotted the saber and thought it was worth the risk as it didn't end up that cheap but it was still a bargain for a nice DT figure.
A couple of mates suggested upgrading the figure which would make sense value wise but I like having the original figure that came with the saber particularly because it scrubbed up so nicely and is part of the whole transformation. I did have doubt's how well it would turn out but I literally used a cotton bud and some warm soapy water and the dirt fell off.