@Tom
I've gone through a couple pairs of those Sony in-ear headphones in my life and I found the biggest problem is that they tended to die within a year or two for me. So, while they were cheap and the sound was decent, they never lasted long. So, lately I've taken to buying midrange stuff ($50-$100) and I've found that the sound is better. I've also found that they last a lot longer--about 4-5 years for me. So replacing a pair of $100 headphones every 5 years is just as cheap as replacing a pair of $20 headphones once a year.
I too would love to try a pair of £500 headphones--and the author does only includes one pair for us to drool at--but I'm glad most of the headphones were in the £50-£150 range since this seems to be about the point where the manufacturers start producing quality work. And to be fair, there were a pair of £30 and £35 included in the article.
Note: So far my Shure SE115s have lasted about 2 years and they cost about $100. I'll keep them until the cable does fray, which it will eventually--or until I get rich and can afford the £500 headphones.