Complex sentence: Eventually the average actual transaction price was near $4.00 per acre-foot ($3.25/thousand cubic meters), as the next best option was continuing to use the land for agricultural uses, which fetched a much lower price.
Split into simpler sentences: Eventually the average actual transaction price was near $4.00 per acre-foot ($3.25/thousand cubic meters). The next best option was continuing to use the land for agricultural uses, which fetched a much lower price.