A few options here without giving up future compatibly within wireless and E-TTL and High Speed Sync:
a) just get a used 580EXII once you can afford it
b) look for the previous model (580EX or maybe even 550EX)
c) same as above for the 430EX series - it's a good flash for most uses, can later serve as a slave; only difference: can't be a Master and the buttons are not as nice as on the 580. I find the exposures actually to be a little more consistent than on my 580.
d) almost exactly the same functionality as the 580EXII but a little cheaper: Metz 58-AF2.
The Metz even has a few little features that are better while maintaining all key important elements (ETTL, HSS, Master and Slave option, etc), e.g the charge confirm beep and that it can be put in a special "group" as the master other than group A. The reason why I decided to buy a 580 instead (even though I've otherwise been a long-time Metz user): the build quality of the Canon appears a little better - but I'm still thinking about adding one of those. Some people don't like the menu - but then again the Canon menu is not very lovable either, is it?