GREAT masterpieces tend to cost a few bob. A Leonardo Da Vinci daubing of Jesus Christ crossing his fingers fetched a record £350million at auction in 2017. So the work of art which Pierre-Emerick Aubameyang produced to settle this FA Cup Final may prove a bargain by comparison. Arsenal surely cannot cash in on Aubameyang after this – he won a penalty, scored it, then conjured a peach of a winner to earn a comeback victory over Chelsea which also clinched Europa League football next season. Now Stan Kroenke – not the most free-spending owner – simply has to make Aubameyang an offer he cannot refuse and persuade him to extend his contract beyond next year. That current deal is worth £180,000 per week. Aubameyang will want it doubled, so it tops the wages of wilderness man Mesut Ozil.And who could blame him? This was the Gabonese forward’s third brace in four matches, taking his season’s goal tally to 29. He is Arsenal’s captain and talisman – absolutely critical to the future of Mikel Arteta’s team. Chelsea had started so brightly and led through beauty of their own from Christian Pulisic. Yet they lost their skipper Cesar Azpilicueta, and then…