So my advice right now is either go really cheap (£30) or go really expensive (£500+). Nothing between the two is worth it. It is a waste of time and a waste of money.
Also seriously think about your desk. My desk was too high and as a direct result I had to depend on the gas-compressor (gas-lift) working fully (to its highest point) or I would get shoulder/wrist strain.
I wound up getting an Ikea adjustable desk. They're less stable than regular desks (I have mine against a wall to stabilise it) but they resolve the height issue.
PS - Don't assume that just because a gas-lift has a maximum weight well above your weight that it will be any more reliable. I got one with a 350 pound claimed-maximum load, and the damn thing still only functioned correctly for six months before it started slowly leaking air.
I second this wholeheartedly. I'm the other way around, in that I'm too tall for regular desks; and it's great having it raised. Good quality and great prices at Ikea for adjustable desks.
My work chair is a Steelcase Leap
http://swordsedge.ca/wp-content/uploads/2009/05/kingconan2.j...
Or, if you are a Dungeons and Dragons geek, you might be interested in the Throne of the Gods for a +10 in coding awesomeness among other benefits.
http://www.poetictech.com/aura/index.html
...and I remember that the price tag was around $15K at the time, but they are super sweet... and can be set to rotate the workstation based on time of day, in order to avoid sunlight glare.
I tend to favour the ergonomic kneeling chairs myself, and I'm on my second in ten years. This time it came from the local Argos store, fwiw.
for example, http://lukethomas.com/100-dollar-ikea-stand-up-desk/
It is impossible to get all four legs to exactly the same length (even if you use the guide marks). He has it resting against a wall for a reason.
I would recommend it, but it might wobble around a little if you put any weight unevenly on the surface.
I have the desk for a year now and it solved my shoulder and back problems from sitting too long.
PS: really expensive though.