I have a reminder set up through data validation whenever certain cells are
clicked on.
I am seeing that some of the users are ignoring the reminder message, just
not noticing it next to the cell.

Is there a way to have a pop up warning/reminder come up whenever one of
these cells are click up, to which they will have to respond "ok" before
entering a number?

The number entered could be anywhere from .01 through 39.99