Amazon offers its Prime members the Patriot Stellar 64GB OTG USB 3.0 Flash Drive for Android, model no. PSF64GSTROTG, for $28.99 with free shipping. (Non-Prime members can spend $35 or more to qualify for free shipping; otherwise, shipping adds $8.05.) That's $7 below our January mention and the lowest total price we could find by $10. This drive is compatible with most Android devices with micro USB and features a transfer rate of up to 140MB/s.