In one end of table cell, concat all text from Cell A when Cell B is blank

In one end of table cell, concat all text from Cell A when Cell B is blank

I've got a spreadsheet of potential expenses in Numbers.app.
Text String | $Price
In some rows, the $Price cell is empty.
I'd like to iterate over all the rows, and when $Price is empty, CONCAT
the text from Text String into the cell.



Example:
Table | $100.00
Chair |
Rug |
Plate | $50.00
---------------
Chair, Rug <-- Concat'd text from Row 2, 3 because Cell B was Blank in each
Is this possible in Numbers.app? I thought maybe with ISBLANK and CONCAT
but I'm struggling to get the syntax right.