I can recommend the Canon LC-5. But it´s very expensive.
If you don´t have the money use the Giga T Pro II...
It's not just about the size of the invoice... One great use for a wireless trigger is so you can be in the picture, and conceal the transmitter in your pocket. I can afford the LC-5, I just don't want to look like a pervert when I'm in a picture.
OMG you left that one wiiiiide open!