Paul,
I check the HobbyKing web site (there is no USA site), if you search for Turnigy BOLT Lipo and they come up. According to the web site you can charge them with a standard Lipo charger and they will act just like a regular lipo but to get them most out of it they recommend their charger. They are available in 2400, 2800, 3450, 5400 mah packs 2S, 3S, 4S & 6S (6S for the 5400 pack only). The 4S 3450 pack is priced at $61.26 USD. It weighs in at 374g (13.2 oz.) not bad.
Best, DennisT