Doorbuster with free standard US shipping at Monoprice, they are offering the new condition Monoprice OTG Card Reader Adapter for $3 with free shipping. You can buy as many as you want. Even if you buy one unit, you still get free shipping. It averages 4.5 out of 5 based on 20 customer reviews. Of interest if the microUSB hardware and software of your smartphones and tablets support OTG.
This may also help lower the shipping fee of any other items you buy in the same shopping cart with it that don’t qualify with free shipping (not sure exactly how this works, YMMV).