Count independent observations carefully
Keep each equipment item and bidder identifiable in your private records. Link revised proposals to their earlier versions. Three revisions from one buyer are not the same as three independent current bids. Similarly, many offers on a single unusual unit do not represent a broad range of equipment.
Describe the sample you actually have
Record the number of units, number of buyers, dates and condition categories represented. Note missing configurations or regions. Do not imply that an average covers equipment types absent from the records. A clear description of the evidence is more useful than an unsupported claim of broad market coverage.
Separate bids from completed transactions
An unaccepted offer, an expired proposal and a confirmed completed sale belong in distinct categories. Preserve the conditions and costs associated with each. A high bid that never proceeded should not silently become a completed-sale comparable.
Report uncertainty plainly
Use the data to identify questions and improve future information collection. Avoid publishing narrow price ranges that suggest more confidence than the observations support. As the record grows, maintain consistent definitions and check comparability before making stronger claims. There is no universal article or bid count that guarantees a reliable valuation model.