The short answer is for several weeks on the trot (on a Tuesday after work) I met a bloke in a public car park and paid 66p per laptop and transferred them from the boot of his car to mine!!!
The longer answer is, I met a bloke at a Car Boot Sale and snapped up all the retro laptops he had (£1 each), went back the next week and he was there again with some more and got them for the same price, then on the third week when he was there again with even more retro 'barn find' laptops - the penny finally dropped and I asked him how many more he had and when he said a couple of hundred I said I'd have them! A couple of them had some technician notes on them with their company logo on it so I did some searching around on the internet and saw that he was one of the early computer recycling companies. The laptops were in a hell of a state and had clearly been kept in a lockup somewhere for years! A bit of foam cleaner and some of those magic cleaning sponges and they've come out a treat!
25% were damaged (but still had either a keyboard, display, RAM or IDE HDD that could be salvaged) and the remaining 75% worked but some had missing HDDs or RAM - which I have been so far able to get from the spares from the faulty ones!
I have well over 300 Retro laptops (and 1 Vintage Compaq 286 LTE luggable) - what I dont have is the room to go through them all and sort them all out 100% - slowly but surely... I have a few old Compaq and HP tablets from around the year 2000 but only 3 of the 12 have pens.
I'm lucky enough to have some storage space at work where I've got about 40 laptops that I still need to sort through and a trolley I use for hauling car boot finds so my lunchbreaks are pretty busy! From the damaged/broken laptops I have litterally kept everything of any use from the CPUs, RAM, HDD's, Screens, Keyboards and even screws!