AC Adapter for laptop computer…problem

My daughter-in-law has a HP laptop computer. The AC power adapter plug
where it plugs into the computer (the little round male plug) has come
loose from the wires. I took it to MicroCenter and asked if they could
put a new plug on it for me. They told me no and said I would need to
buy a whole new AC adapter which is $79.99. so expensive.