What is a reasonably priced drive I can back up my computer to. I am not that computer literate

You can use literally any inexpensive external hard disk drive. Speed is not important.

Seagate, Toshiba, Western Digital all make external hard disk drives of roughly the same quality and in the same price range. None are particularly any better than any other.

For reference: Backup disks for Time Machine - Apple Support

Pick the price range that suits you; you can't hardly go wrong. We all have our favorites, I favor Samsung T7.

Be safe; get two and set both up.

https://www.amazon.com/External-Hard-Drives-Storage-Add-Ons/b?ie=UTF8&node=595048