Hi,
If your initial price is in, say, D10, and
If your initial received date is in, say, C10

then in another cell:

=IF(C10="","",IF(C10<(TODAY()-90),D10*0.7,IF(C10<(TODAY()-60),D10*0.8,IF(C10<(TODAY()-30),D10*0.9,D10))))

This will give you the price as you want, changing automatically as the
initial date becomes over 30, then 60, then 90 days old.
Is this what you need?

You can probably just fill across or down for other columns, but I would
have to know the layout of your sheet to be sure.

Regards - Dave.