Just picked up a pair of these (X1s) from Amazon for £17 inc. delivery.
Initial impressions are fair. I believe that, for this price, sound quality is good. There's a bit of an emphasis on the bass and mids - the high trebles aren't great, but acceptable.
I bought these to replace my Vivanco Aircoustic in Beech Wood, which I picked up on a whim at the start of December as they'd been selling for £9.99 delivered on Amazon. My Vivancos absolutely blew me away for the price - I could not quite believe how good they sounded. Unfortunately however, they are now close to perishing after just a few months.
The Klipsch's aren't as good as the Vivanco's. They do, however, sound a bit better than the Sennheiser CX-200s (which also aren't bad, but a bit fatiguing and too bass-heavy to my ears).
In summary - a pretty good buy, quite cheap, but if you look around and see those Vivanco Aircoustics for a tenner again... grab those instead.