Looking for PC or Laptop recomendations

Hi, I'm looking to buy a gaming system for my brother. He will be playing and running steam guys and applying mods to various games. I'm looking for something on the cheaper side, will probably get it used but I just don't know where to even start looking. A PC or laptop whatever he needs. He just wants to be able to use a keyboard and mouse and run steam games. Any tips welcome please and thank you !!!