A year ago, pre-owned 18-karat-gold luxury Rolex Cosmograph Daytona replica watches with a green dial — nicknamed the “John Mayer” by aficionados, in honor of the guitar-wielding watch geek who helped make it a celebrity must-have — were selling for $52,000 on the Shop, a prominent online retailer of fine 1:1 US fake Rolex watches. Earlier this month, the same model went for $96,000. The sporty high quality replica Rolex Milgauss watches with a blue dial is on fire, too, with secondhand prices on the site spiking to $14,500, from $8,200 a year ago. Ditto the Explorer II model, which has nearly doubled,…