ThinkPad's are typically brought up by businesses. When it comes to replacing their laptops after 3 or 4 years of use, the old ThinkPads often end up on eBay. Hard wearing and easily upgradable second hand ThinkPads are an excellent choice for a general purpose laptop.

I recently purchased a Thinkpad x230. Picked it up from eBay for around ~£240, spent an extra ~£40 for an SSD, installed Kubuntu and I'm finding it to be a solid laptop. I got the version with the IPS display and with 16GB RAM + SSD it runs well, very pleased with what £300 got me.

A useful buyers guide can be found here