We recommend using a third-party analytics software to measure the sales ROI of your PriceMe campaign. You can segment your traffic by source to view the ROI of PriceMe's traffic.
Please find a document that here that explains how to segment and view conversions using Google Analytics:
1) The ROI tracking software previously available in the Merchant Portal has been discontinued.
2) You can still view the number of referrals by category and product (available in the report section).