The trailer offers potentially more difficulty at the border crossing than the glider. Buy the trailer with a separate bill of sale, leave the Canadian tag on it, and take the Canadian Title with you. You will have to mail the Canadian tag back to the owner so they can turn it in, and use the bill of sale and Canadian title to get you a US title for the trailer. For payment you can buy a draft from a Canadian bank in Canadian$ from your US bank. The airplane stuff is pretty straight forward as others have described.

SF