@PurrJPro You can't go wrong with @tuxedocomputers but it's gonna be hard to stay under 1000USD. Everything they have runs beautifully with linux and their support is far better than you'll find anywhere else. I've bought more laptops over the past 20 years than anyone probably should, and finally going with #TUXEDOComputers was worth the little extra I spent on it.
If you want to just buy some cheap laptop off the shelf, that's okay too, just do your homework first. Find out what hardware that exact part/model number has in it so you can know what sort of problems you may be dealing with later. I've bought at least 2 different models each of Sony, DELL, Acer, ASUS, HP, IBM, Lenovo, Apple, Compaq, 5~6 different off-brands I can't remember. Some work great with no hassle at all, some take loads of fiddling, and some have hardware that just doesn't work at all.