My option would be to get Elinchrom skyport or PCB Cyber Sync. Both options are cheaper than Canon's ST-E2. They are also compatible with other strobes that you might later procure.
This is just based on my research for future purchase. As DmitriM said, the Youngnuo's are really cheap.
Yongnuo is awesome for non-ETTL triggering. Hehehe triggered it by accident in a car the other day.... so yeah, it goes through walls and cars and has pretty awesome range.
