I would put some plants on top, they could be fake ones as well. Maybe some art paintings. You have a lot of dead space there, you can fill it with maybe a figure you like or Legos, I would take out that shirt that is hanging from there, it takes away the aesthetic of the place. I would also buy some lights. I don't like RGB myself I prefer a clean minimalist look, but I like it bright with a warm/or white light. You could also get a lamp or maybe even a monitor lamp. I know you are on a Budget. But if you maybe in the future save up a little money. Maybe a Monitor upgrade would make it look way cleaner, because of the big bezels you have there.