not too sure where to get sunpak flashes...apart from B&H...might wanna try TCW?
HJ has the 32Z2 whereas i have the 32Z1...think the difference would be the guide number. HJ's one is more powerful if i m not mistaken.
i think any of flashes would be able to work, provided it is a standard ISO flash (center pin) and of course, be careful with the triggervoltage. oh, forgot to mention, try to get the flash with zoom....useful when you need to shoot faraway scenes while utilizing that long zoom lens of yours...
tried my friend's canon EX420 TTL flash...the fz20 managed to fire it off, damn powerful though...cos it doesnt have Auto modes, or at least i didnt know how to activate it.