Yes, I think that some $100-200 computers are good enough to use a web browser at a good speed.
But, if the operating system on cheap computer is Windows 7-10, there would be some speed problems when using a web browser because Windows doesn't work very well on 1-2GB RAM in my experience. 1-2GB of RAM is still very common on a lot of cheaper computers which cost $200 or less.
Linux based operating systems like Linux Mint, Chrome OS, Arch and Debian Linux runs most web browsers at a fast speed even when there is less RAM, and a slower CPU.
But, if the operating system on cheap computer is Windows 7-10, there would be some speed problems when using a web browser because Windows doesn't work very well on 1-2GB RAM in my experience. 1-2GB of RAM is still very common on a lot of cheaper computers which cost $200 or less.
Linux based operating systems like Linux Mint, Chrome OS, Arch and Debian Linux runs most web browsers at a fast speed even when there is less RAM, and a slower CPU.