City offloaded five ageing, long-term servants since the end of the season - including full-backs Gael Clichy, Bacary Sagna and Pablo Zabaleta - along with Jesus Navas and 'keeper Willy Caballero.
The fee would be inflated by his 'homegrown' status, as Guardiola seeks to satisfy the Premier League ruling that requires teams to have a minimum of eight 'homegrown players' in a 25-man squad - but big fees rarely deter Manchester clubs.
Previous Englishmen have struggled at the Etihad, including the likes of Jack Rodwell, Scott Sinclair and Fabian Delph - but Walker would be more than a squad player to appease quotas.
The England international would almost certainly be a guaranteed starter next season and significantly increase City's already lethal attacking threat, while bolstering defensive weaknesses with athleticism to track back.
Guardiola's perfect start in England fell apart during October last year, primarily due to defensive and goalkeeping frailties. Those recurring stutters in form cost the Spaniard a genuine title challenge during the closing months.
However, with new keeper Ederson signed from Benfica for £34.9m in June and, potentially, one of the league's most formidable full-backs added to the ranks, Guardiola is setting his stall for a title-challenging second term.
But how would Walker improve City's stats?