If we're talking about a per-unit price, then the trigger that meets all four requirements is the Yongnuo YN-622C. They cost roughly $85/pair (as of the time of this writing). They communicate the full hotshoe protocol, but do require that your camera is DIGIC 4 or later (i.e., has the flash command menu), and that your flash is menu commandable (e.g., a 580EXII, not a 580EX), since it's the camera menu/flash control interface that's being used to change the settings on the flash.
There's a rumored YN-622C-TX unit that might eliminate the need for menu commandability on the camera side. The Nikon version (YN-622N-TX) has been released (where it's obviously much more needed, since none of the Nikon bodies do the Canon flash menu), but the Canon one has yet to see the light of day.
In addition to communicating eTTL-II, HSS, power settings, custom settings, zoom, etc. etc., the YN-622C triggers are also capable of "supersync" ("hypersync" in PocketWizard terminology, and aka "tail sync"), which allows for faster-than-max-sync shutter speeds with manual lights by firing the flash early at full power, and then lighting the frame using the "tail" of the burst where the illumination falloff is more even.
CliveyBoy's "The Other YN-622C User Guide" has most of the details about the YN-622C function and compatibilty with cameras, flashes, and studio strobes.