I do not know the price well, but Pico4 in amazon second hand cold be an option (if you are lucky) and you neet to plan 15 USD for virtual desktop.
On the sub 50 usd , i did experiment VR on the cheap with smartphone google (30 usd), and a software called IVRY avaliable in steam… The result is vr on the cheap, but does not match any dedicated VR device to me.
This is my humble opinion.
Have anice day all