Newegg discounts select flash cards and flash drives, as listed below. With free shipping, that puts most of these items at or near the best price we've seen for these cards and it's the lowest total price we could find by at least $3. The deals:
Amazon offers the SanDisk 128GB Ultra UHS-I microSDXC Memory Card, model no. SDSDQUA-128G-G46A, for $119.99 with free shipping. That's the lowest total price we could find by $80. It comes with an adapter and purports to be water-, temperature-, X-ray-, magnet-, and shock-proof.
Note that it's expected to ship in four to six weeks.