Where in Canada are you?
I know, here in BC there are a lot of areas you can buy citrus from. There are 2 places most common, one, being in delta, the other in sidney on vancouver island. I dont know if either ships. Could be worth a try. I know the one in Delta has a ton of varieties, unfortunatly, many are in the 5+gallon size, so quite hard to pack up and ship. I just had someone ship me, privatly, 4 trees, but they were all little grated ones, easily sent bare rooted. No clue how to send one that big, otherwise I would help.
I also have come across a site in Quebec that has citrus and they do ship... but I dont trust it when they wont guarantee their shipments, so that closed me off from them fast!
I've been able to get meyer lemons, lisbon, ponderosa, limequats, key limes, tangerines, plus a couple others.
the guy in delta was the best to work with though. he met me at the greenhouse... he is more a private hobbiest that shares. great prices and works with you. He was amazing. He even gave me a TON, like 20 pots (1 gallon size) which was soooo amazing as I had a zillion key lime seedlings needed to be moved into larger pots.
there are also many areas around Kelowna that carry citrus, most of the greenhouses do, even if not advertised. Not huge selections, but still, several good ones. Bc definatly has the citrus market in Canada though. I was searching for so many years in MY area... and then, after years, finding out I had driven past so many greenhouses that carried them... drove me nuts. But I have my trees now, 10 varieties and will be increasing that ammount by several come next month. just 3 weeks before I get my trees!!! Yep.. I am obsessed with my trees
One thing I DO recomend, if wanting a key lime... grow from seed. Its one of the fastest growing from seed and will come true to type. others will take 7-20 years to get to a fruiting stage... so I gave up on most my seedlings. I'm not waiting until I am 50 to get a grapefruit when I can go and buy a tree already fruiting. I'm not that patient.