What is "to be had"?

Hi all,
I can not figure out the meaning of this expression.
Can anyone help me?

"I've been had" is colloquial for "I have been deceived" or "I have been cheated."

When what is to be had is a thing, not a person, "to be had"means "available." Rings are to be had at a jewelry store. Used clothing is to be had at a flea market.

Thus, the expression has the two above meanings - one 'to be cheated' and the other 'to be obtained'.