Despite the myriad of techniques for calculating flexibility envelopes in buildings and power grids, their analytical monetization has received practically zero attention. This obscure issue reaches even more unknown depths in the multi-period (MP) setting, where intertemporality hinders the design of a clear pricing framework. This letter builds on the author's previous work, which proposed a novel methodology for the one-to-one flexibility-to-cost mapping in grid-friendly smart sustainable buildings (GF-SSBs), and discusses alternatives for mapping MP flexibility envelope to costs in practice. Their comparison provides key insights into how different cost structures may affect end-user behavior and the grid's ability to procure flexibility. This letter hopes to kick-start the discussion around “fair” or intrinsic flexibility value, an issue that has largely been sidelined.