My wife has purchased onesies for me from: baby-pants.com. Their stuff is great quality, good customer service, and they have a good selection of colors. They also have directions on how to get just the right size. Good luck, they work great.
eBay seller--mslorainex has onesies in various colors including blue and gray. I have purchased from her; I enjoy her products and she seems to be a reliable seller. Her listing says she ships to Canada.