Yep, pitchers and basins were basically plumbing for those that didn't have any. Add in chamber pots for a fuller picture.
These items typically date from the early 19th century, around 1820 or 1830, up to the time that plumbing became the norm in most houses in the early 20th century. Before 1820 it was only the British and American "upper crust" that believed in bathing frequently; it was quite an "avant garde" notion. Most everyone else bathed, at most, once a month, or - more frequently - once a year! And even then bathing was pretty much confined to the skin that was visible.
*pause to consider this * **shudder**
Not everything was better in the "good old days."
And yes, they do have value. Like anything else, it's relative. A typical pitcher and basin, used back in the day and with a chip or two, will go for $75-$200. A full bathing set, with soap dishes, chamber pots, and even cups for early toothbrushes, can go for many hundreds of dollars, depending on maker and condition.
