If you're going to get the Duo with it's builtin balancers, whatever you buy now will be obselete when the Duo arrives, so I'd keep it as cheap as possible and still be functional. Astro Blinky sounds like way to go. If you have a dvm might check and see how far out of balance they actually are, you may be lucky and find they are not that bad.

Balancing after charging is not a good as doing it together - after you lose some capacity as balancer evens voltages out.