Buying a car in the US on ebay and importing it to Canada seems to be a remarkably easy thing to do! You can drive the car home. This is how we did it to bring a vehicle to BC. Your experience may be different, of course...
1. Make sure your vehicle can be imported. Go to riv.ca/english/US_vehicle_admissibility.pdf to figure out if your vehicle is eligible.
2. Find out if there are any outstanding recall issues. Usually the manufacturer website or a dealer or the seller can tell you this. Note: if you want to take over the balance of the manufacturer's warranty, this might be tough - check what modifications will be required with the Canadian mfr (like a new speedometer); this could get pricey.
3. You're going to have to drive the vehicle for a few days at least until it can be registered in Canada, so you will need to have temporary tags from the place where it is presently registered. If you are buying from a dealer, they will probably do this for you. Otherwise the current owner may be willing to let you use their current registration. If neither works, it gets complicated because you need to get approval to cross each state as you drive home. We didn't need to do this, and I have no other suggestions how to avoid this pain, except to have the vehicle shipped to a state bordering your province.
4. Buy the vehicle. Get a copy of the title certificate and a bill of sale faxed over, and the originals by courier.
5. Figure out which border crossing you plan to drive across, and fax them a copy of the title certificate. You need to do this at least 72 hours before you show up. See cbp.gov/xp/cgov/toolbox/contacts/ports and make sure they are open when you plan to be there. A quick call to the office to make sure is a good idea.
6. Get an "insurance binder" from your local insurance company. Give them a call to make sure this is right in your province. In BC, it was easy to get this from an autoplan agent.
7. Drive the car to the US side of the border and let them compare the title certificate with the one you faxed them, and to confirm that the VIN numbers match.
8. Drive across the border and tell them you are importing the wehicle. You'll have to park it and fill out some forms and pay GST.
9. Drive home and celebrate. Wait for the forms from RIV. These forms tell you what needs to be changed in the vehicle. If you're impatient give them a call and ask the form to be faxed to you.
10. If you plan to drive the vehicle while you wait for the forms you will need temporary operating permit. During this time you can get the daytime running lights enabled and whatever else is required.
11. Go to your closest Canadian Tire store and have them check off the RIV form. They will also need the title certificate, the letter proving that all recalls have been performed, and the form you got from Canada customs.
12. When the customs form has been stamped by Can Tire, you can get the car registered in Canada and insured. You may need to pay local taxes again...
I think that's all! Have fun!