The Nitecore UM10 and UM20 (dual) aren't bad chargers for the price, have a useful cable management system and the display is useful. But the fact that they use a micro USB connection is IMHO the best feature.
I picked up a UM20 from Amazon (I'm a Prime member) for $15 shipped and it does the job. The dual battery model seems to work best from a 2A USB wall charger since it can then give a full amp to each battery. But does also work from my desktop or laptop's USB 2.0/3.0 ports, and from an anemic 0.5A USB car charger, though obviously slower.
Just don't get too hung up on the pass-through charging of the UMxx. It really only charges one thing at a time, either the battery(ies) or the external target (phone, etc) via a "priority" switch, and won't charge the other until the first is full. But it is handy to use one wall charger or USB port on multiple devices once you're aware of the limitations, since it is a lot less cable hassle.
just wish the battery wasn't such a PITA to get at. but it sounds like the charge port does a good job....
