Suggest me a laptop for Linux

I wouldn't suggest specific brand , but just some pointers - choose AMD , without OS or DOS - don't choose Linux pre installed because some laptops are costly with pre-installed OS.
I had bought HP with DOS and it was comparatively cheap with i5 and nvidea 820M .

In this budget I would strongly consider a Lenovo Thinkpad perhaps a T series. They are often compatible with Linux out the box and ordered in bulk by businesses and schools meaning you can find them discounted on sites like eBay

Hi, I'll recommend hp probook 430 series, you can specify hardware to match your budget (basically you need just 256gb ssd and 8gb ram, this model is easily extendable)
there is no pain with installing ubuntu or troubles with drivers
personally using it for more than a year, no problems to this day

I just want to warn you about nvidia optimus technology. I had huge problems with Dell G3 and linux because of video drivers incompatibility. There was preinstalled Ubuntu on this laptop, that's why I thought that Dell G3 works fine with linux distributives. But as it turned out, Dell made their own version of Ubuntu for this laptop. That's why my next graphics card will probably never be made by nvidia.
Pop!_OS from system76 become the only solution in this case. By the way, they specialize in selling professional customizable laptops. You can consider their products if you want, but I have no experience with their stuff. system76.com/laptops