Be aware that a slow cooker and a crock pot are two different things. A crock pot is merely any cooker that has a ceramic cooking vessel. It may or may not be capable of slow cooking.

My slow cookers are labelled thus:

      Rival
    CROCK POT
Ceramic Slow Cooker

They were not expensive and they work fine. Have done for years.

However, the small one has a plastic lid which didn't last. I use a glass cover that came with a glass bowl on it now.