I think there may be 3 systems at issue:
-the "bulb" is a manual pump system, maybe 2 different makers, available at CW
-I understand the $300 WRV system to be an electric pump system with reservoir, that's manually activated with a switch.
-I haven't seen a gravity fill system, which if available might be more fully automatic
I bought the bulb pump system and I'm happy with it. Pretty easy to install amd the hose can be routed around the box (to eliminate box removal for filling)
CW had them on sale recently. (Good thing since each kit only serves 2 batteries and the bulb is extra)
2004 Alpine 34 FDDS
Anaheim Hills, CA