You own your life - why not spend your own money for the things that make you and your life better?
Who cares?
I worked at a job where I had a small, crappy monitor. I made decent cash. I just bought a large decent monitor and brought it into work. I ended up using it for many years. My life was significantly better. I've done that at several jobs since then, and NEVER regretted it, in fact it was one of the soundest decisions I've ever made. Also keyboard and mouse.
There are so many people using the default keyboard, the default monitor, the default tools.
If you push work to do it for you, you need to challenge the "everone gets a dell 19" monitor" b.s. If you push your boss, he might have to do justification paperwork.
Just become what you are.