is it possible/would it make sense to use a Canon flash like the 580 EX II or the 430 EX in conjunction with a lower-cost unit like a Vivitar?
I'd really like to have a Canon flash for possible on-camera use and combine it with a second flash for those Strobist-style setups. However I'm a bit put off by the pricetag of buying two Canon units.
The flashes are supposed to be linked using a wired connection (for starters) to a 40D. If you have an idea how to do that, please bring that hint forward too