http://www.staples.com/Staples-Mont...-Managers-Mid-Back-Chair-Black/product_853617 I got this chair last month along with a cherry bamboo chair mat for ~$110. Pretty awesome deal.
I recently bought a Tempur-Pedic TP8000. about $300. So far so good. I found it to be more comfortable than Herman Miller chairs and most of the chairs that cost over twice as much. I definitely tried some chairs that were around a grand that I liked better, but I didn't want to spend that kind of money.
Be careful of what you buy. A lot of the cheap chairs aren't designed to be sat on for more than a few hours a day.
I use a laptop at home so I can switch positions; do whatever is comfortable. Sometimes I curl up on the couch and put the computer on the armrest or rest it on my leg. Sometimes I lie down flat on my stomach on the floor. At work, whatever chair they gave me seems to be working fine. of course, sounds like a lot of you guys have extra, ummm... considerations in terms of activities at the computer.
I don't have a picture of the chair and desk at work, but I don't quite fancy it. Makes you sit up and stuff. And one of the wheels disappeared to I don't know where. But the view of the city is nice. Still have to get up and walk around every 30 minutes or so, though.
if you want a simple, extremely comfortable mesh chair check out the setu chair from herman miller. it's quite a good deal for how rad it is.