Cheapest possible HTPC build

I've an incredibly tight budget and want to build something that can play any media file I throw at it without fuss. It won't be used for anything other than playing videos in my bedroom so the requirement list is pretty minimal:

Can play 1080p .h264 videos comfortably, not dropping any frames.
Preferably matx unless I can save much more money with a regular system
HDMI output
UK based build (ie no builds based on rebates or Newegg deals which I can't get)
Don't need an especially large hdd and only need enough ram to do the job

Cheapest I've been able to price up is around the £200 mark. Any chance of one closer to £100?

Thanks in advance