a famous chinese travel agent in GTA and VAN, tianbao(?) travel, which offers great fare on flight to china. but sometimes it's a little bit difficult to get a sales answer your call, i've been there once, they have so many calls, that i can't believe how their sales dealing with those calls! but if you are lucky, you will get a great fare quote!
their web www.tianbaotravel.com
btw, their tour packages are great too!