So, on the same lines, I've started a new job and I'm able to claim back some expenses for some items, namely:
(Wired) Keyboard and mouse (£40)
Chair (£80)
Monitor (£100)
Desk (£120)
In terms of the monitor, it's just going to be office-type tools so response time isn't an issue at all, and I'm willing to go over that budget (somewhat) to have a set-up that will work in the long run. As I'm using spreadsheets for it, would the wider-shaped ones be decent to have? I can't find the page now, but there was a 27" one with a 21:9 ratio that I liked the look of.
I recently got a 27" for homeworking and I love it, although it cost rather more than £100. Cheaper 27" monitors (under £200) will probably be 1920 x 1080 (HD) while more expensive ones will be 2560 x 1440 (QHD). Higher resolution will give nice crisp text but support will depend on your PC/laptop graphics driver and outputs (VGA, HDMI, DisplayPort etc.)
With an HDMI connection I belive the maximum resolution supported is 1920 x 1080 for most PCs while DisplayPort will allow 2560 x 1440 (if your graphics supports it). If you are limited to 1080p obviously there is no point forking out for a 1440p monitor.
Like TVs there is a lot of tosh spoken about dynamic ratios etc. which are impossible to compare because each manufacturer uses their own metrics.
Fast response times are often associated TN panels which are generally cheaper while IPS panels tend to give better colour reproduction and viewing angles which might be more important in a non-gaming context (outside of hard core gaming, I am not sure that this is even an issue with modern IPS panels).
I generally avoid built in speakers (usually rubbish) but would spend a bit extra for a stand with height, swivel and tilt adjustment (important for comfort in a homeworking set up). Annoyingly few manufacturers offer this - Dell and Benq are among the exceptions. I also have built in USB hub which is great if you are short of USB ports on your laptop/PC and don't want a separate powered external hub.
Some of my colleagues have moved on to two screen set ups which can improve productivity (depending on your workflow). If this is likely you will want narrow bezels and probably a better known brand if you want to be able to find an identical second screen a few months down the line.