Allison and Nick Bracken purchased a 12-meter school bus on eBay in June 2021 for $5,000. ^[1] E-commerce search ranking must balance multiple objectives including relevance, user engagement, and platform revenue when allocating impression slots to competing listings. ^[2] Estimating expected revenue is well understood for fixed-price items but becomes challenging when inventory includes mixed listing formats such as pure auctions and hybrid 'Auction with Buy It Now' (ABIN) items. ^[3] Online A/B tests at a large e-commerce platform showed positive revenue gains and statistically significant improvements to user metrics. ^[4] The authors extend the standard Expected Cost-per-Mille (eCPM) framework by deriving a marginal eCPM (meCPM) that captures the incremental value of showing one more impression of an item whose price is still evolving. ^[5] The couple converted the bus into a mobile home over a period of less than three years using YouTube videos as instructional references. ^[6] The total renovation cost for the bus conversion was approximately $40,000. ^[7] The couple now travels through the United States and Canada in the converted bus. ^[8]