I use one of these:
Or you can use one of these as well:
The latter is a 15-amp version. It would probably safely power one charger, but I wouldn't share the power supply with two chargers.
I'm planning on using the 25 amp version for two Pulsars, should be plenty enough for both.
Since any of the power supply comes with only one banana plug port, you can just stick one of those Pomono banana connector to make it accept two banana jacks, one in the rear and one from the side...
The astro stuff will work good too. If you're really on a budget, you can always buy a 300W power supply for computers. Just isolate the 12V supply plug and solder a banana receptacle or whatever other connector your charger connects with...