Hi Charles,
If you set the Single/Sole Indicator, the vendor's effective price is regarded as the market price when the system calculates the score for the criterion Price Level. Consequently, the market price and the effective price are identical. Because there is a variance of zero percent, the vendor receives a good score
If you do not set this indicator, the single/sole-sourcing situation is not taken into account. The system does not determine a score for the price level based on this material.
Please refer this link -
Price Level (Main Criterion “Price”) - MM Vendor Evaluation - SAP Library
Regards,
Akash