Look no further than a factory refurbished X series model. Depending on how recent the model is, but definitely not more than 500€ (not even £) to get something way more powerful than a 2011 MB or MBP.
Where should I look to if I want one? Do I go to Lenovo's own website? They're not too clunky and heavy to bring around right? Which X models should i be looking at?
As a keyboard person, perhaps you first decide which keyboard you want first, X220 to X230 is the time of design change:
Anything around that time, even for X240 refurbished grade-A is around 400€, on Google search or eBay.
But I warn you not to get the X240 if you want to experience the trackpoint experience first-hand because they took away the red Thinkpad Trackpoint navi buttons on X240, everyone complained that becomes not so usable (China way of cost cutting or smart-ass design modifications instead of building upon heritage by Lenovo 'R&D', teams still led by non-Chinese though), and they had to bring it back on the X250. Just top it with a model with core i7 and SSD.
I was a Lenovo authorized service tech on the X220/230 for a few years and can confirm they are my favorite thinkpad computer from around that time. I can't comment on IBM thinkpads, but an X220 is an excellent computer. There were some issue with the screen / hinge, (we had the convertible tablet version) but very easy to work on, not very fragile (I can't comment about the laptop version, that screen looks fragile to me) and pretty drop-proof.[/spoiler]
Many of the old IBM thinkpads used NMB keyboards, I think the X60 did and maybe the X40 also. They were pretty good!
Does the X220 has NMB keyboards? And who are the new OEM for the new ThinkPad keyboards?
I have been using ThinkPads since 2003 or 2002, I forgot the exact year, but I started with T series. I have both X61t and X220t (tablets) and I like X220's (same in the tablet or T420) keyboard slightly better because of its community driven design changes (bigger Del & Esc keys, and a dedicated microphone mute button). The most complain people have about ThinkPad's keyboard is the Fn key position at the very corner, it later has BIOS supported swapping of that key. For me, what it doesn't make sense most is the Fn+Space combo to change screen resolution - it would make sense instead if they use a system like OSX where they can activate an under-the-cursor magnifying lens window.
My ideal laptop is a X220 non-tablet laptop with customized CPU and screen (to FHD or higher) upgrade. I'm not ready yet to jump into the new keyboard design despite many good reviews, plus I really like the extra large Esc and Del keys. My X220 tablet survived 2 drops but the little studs on both sides of the keyboards fell off and I spent like $60 to replace the bezel and palm rest just for cosmetic repairs. A tablet is still something real good to have especially when you use Windows and MS OneNote or any inking software the pressure-sensitivity enhancements.
I really like the TrackPoint, and I wonder what pointing device can really replace it while keeping a similar home-row philosophy.