Try to replicate the original packing as much as possible. In a static bac, in a bubble wrap sleeve, and in a box that prevents it from being smashed and flexing.
A little higher than your $250 limit, the Pixel 3 Xl 64gb is $299 new at B&H.
https://www.bhphotovideo.com/c/product/1615542-REG/google_ga1296_us_pixel_3_xl_64gb.html
Maybe think back to KB's and mouse's you liked in the past and look for something similar or upgraded versions and try those out? Heck I rock some old IBM keyboards at work because i like the tactile feedback and a bonus is the clicks drive the narcissist mad that sits in the next cube over.
I don't use one but was the "mouse guy" at work. Not too many used this but those that did say it lessoned the pressure on their wrists. You can feel the difference in the bottom of the wrist if you merely hold you hands in the horizontal and vertical mouse positions. It was not for me. My...
Multiple PS from the 2008 or so still plugging along. The quality products outlasted the cheapo stuff by a long shot. I can't recall any of the good ones going bad. Blow them out every 4-6 months and keepem from heating up. I read that dust coating a PS is like wearing a heavy coat in a warm...