At the core, this formula uses the COUNTIF function and an expanding range to count occurrences of values. The expanding reference is used so that COUNTIFS returns a running count of occurrences, instead of a total count for each value:
Next, 1 is subtracted from the result (which makes the count of all non-duplicate values zero) and the result is multiplied by 0.01. This value is the "adjustment", and intentionally small so as not to materially impact the original value.
In the example shown, Metrolux and Diamond both have the same estimate of $5000. Since Metrolux appears first in the list, the running count of 5000 is 1 and is cancelled out by subtracting 1, so the estimate is remains unchanged in the helper column:
=C8+(COUNTIF($C$5:C8,C8)-1)*0.01 =C8+(1-1)*0.01 =C8+0 =C8
However, for Diamond, the running count of 5000 is 2, so the estimate is adjusted:
=C11+(COUNTIF($C$5:C11,C11)-1)*0.01 =C11+(2-1)*0.01 =C11+1*0.01 =C11+0.01
Finally, the adjusted values are used for ranking instead of the original values in columns G and H. The formula in G5 is:
The formula in H5:
For detailed explanation of these formulas, see this example.
Temporary helper column
If you don't want to use a helper column in the final solution, you can use a helper column temporarily to get calculated values, then use Paste Special to convert values "in place" and delete the helper column afterwards. This video demonstrates the technique.