I don't know if there is a better way to do this, but what I have done with big ticket items (i.e. electronics / bicycles / cameras etc.) is head to your nearest CBSA office (I usually go to the one at YVR at the International Arrivals terminal) and show them the item with any documents. They will provide you with a green card/ticket with a stamp that indicates it came from Canada.
Having said that, on your way home, it doesn't guarantee a free entry home. CBSA officers may or may not question the validity of the item again so have all your ducks in a row including any paper work. I once brought a bicycle home but they were unsure if my bike was modified so I showed them my original invoice (photocopy) and the bike itself, parts, and serial number etc. and away I went.
Again, there may be a better way and someone with more knowledge an experience - please correct me if I am wrong but I am simply speaking from my own personal and recent experience within the past 2 years.
Oh, and good luck and congrats!
