I like this flash: Yongnuo YN468II for US$82 with free delivery from China. http://thephotogadget.com/content/yongnuo-yn-468-ii-ettl-ii-…
Did a bit of research, thought I would share. Not a bargain because its the normal price, but I search ozbargain for old forum posts if I am after something, so figured this might assist someone else.
From what I can tell, what you are after in a flash is for it to use the onboard clevers inside your camera - to use "through the lense" (or TTL) metering to work out how much flashyness to fire off rather than using its own external flashy metering. To use the technical description. http://en.wikipedia.org/wiki/Through-the-lens_metering
I have a Canon SX40HS camera, which goes for under $500 so didn't want to spend a heap on an external flash. Canon Speedlight ex90 looks like a marginal improvement on the built in flash at best (http://www.kenrockwell.com/canon/flash/90ex.htm) and goes for about $100. After a bit of googling found a report of SX40HS and TN468II being compatible, so I'm giving it a spin.
Cheers,
MrDixit
I picked up a YN460 for about $35 about 18 months ago. Doesn't have TTL metering, but I use (M)anual shooting in RAW so I can make minor changes later if I need to. I also occasionally use it as a slave. I'd be interested to see how the TTL model works out as there's a lot that can go wrong. The AF beam is very handy too.