Nice subject!
I am neither willing to spend a lot of money on the latest hardware nor do I want to upgrade my stuff all the time. That’s why I am using low budget stuff from the second-hand market.
Over the years I have accumulated a handfull of laptops and flashing tools for coreboot. I started with libreboot and Parabola, failed to get the first versions of Qubes running on an old Siemes laptop (vt-x and vt-d were all Greek to me back then).
So, if you’re willing to experiment, get some flashing tools and start tinkering. Used tools can be bought for a song. For example, an old raspberry pi costs 10 bucks or less.
Regarding laptops the Lenovo G505s with an A10 AMD is best suited for experimenting because after flashing it is almost 100% open source (put in an Atheros Wifi module) - no Intel ME/ AMD PSP.
You can flash it by either taking it apart and flashing the BIOS chip or if you’re lazy & still able to work very concentrated you could also carefully cut a hole into the plastic that is covering the BIOS chip with a hot knive and flash it without needing to take the whole thing apart. I’ve done it both ways and both laptops are still working (years after flashing). Once flashed with coreboot updating coreboot can be done internally. Only if this fails it has to be flashed externally again. Then the little window mode is much faster. You could apply something in order to close the window again…whatever you want. The advantage of cheap stuff is that it doesn’t hurt so much when breaking it. I still hate it so it never happened for me this way, there were only natural causes of death like thunderstorm accidents.
The whole process is explained in great detail on the following website. It’s updated regularly:
http://dangerousprototypes.com/docs/Lenovo_G505S_hacking
The laptop usually costs around 100 $/€ but if you’re lucky it can be even cheaper. I bought one for 30€ and it was like new (it was advertised as dead but after flashing it came back from the dead). The other cost me 120€. There are different versions of the A10 with different discrete GPUs, the HD-8570M and the R5-M230. Both have 2GB and both work. With 16GB of RAM this laptop works very well with Qubes. It isn’t the fastest (just search for G505s, I’ve written down some startup times a while ago).
Another Thinkpad that works very well with Qubes is the T420, with or without coreboot. Also cheap, around 100-150.
I also tried out other laptops which don’t fulfill all requirements for Qubes, for example the Lenovo W510. It works with Qubes 4.2 but it lacks interrupt remapping. You can put 32GB of RAM in but you have to try the memory slots one by one. I think it’s best to start with the two below the keyboard because the two on the back are easily accessible. When the laptop is starting with 16GB below the keyboard it should work with the other modules as well. The thing is, if you put in all at once and the BIOS is complaining with a beep signal then you have to start over anyways.
I read a little about interrupt remapping and I think it does mean that without it Qubes lacks some layer of isolation but I don’t know the gravity of it.
I guess, for private use or experimenting it shouldn’t be the biggest problem, should it?
Another thing I noticed is the NVIDIA Quadro and sys-gui-gpu is working out of the box. Well, I don’t know if it’s working as it should because apart from trying out some stuff I didn’t do much. What I mean is, I set up sys-gui-gpu and put my Quadro card + HDMI in sys-gui-gpu, reboot and it boots into sys-gui-gpu. By todays standards the graphic card is anything but fancy, 1GB, but maybe it could bring some performance improvement. I know it does with other systems. I didn’t test much because I had trouble with how to deal with dom0 tasks in sys-gui-gpu, so I didn’t inquire much further if the graphic card is even recognized/made use of. Well, I tried, installed proprietary drivers but then I got stuck because of some nouveau/nvidia intolerance. I know that one of both has to be blacklisted at boot level in order to not mess things up but in connection with sys-gui-gpu, I failed to make progress until I lacked motivation.
Maybe for experimenting this laptop would also be okay. It shouldn’t cost much more than around 150, of course, you probably won’t find it with lots of RAM. I had several modules for all my laptops so it wasn’t hard to max out at 32 GB.