From my recent experience, (buying a car in PA), it's not a given that a Canadian buyer can get a title with out of state address. What you can get is a title transfer (in PA, notarized), which will then allow you to export the car from the US and register it in Canada. Also from experience, bring a copy of the advertisement for sale, showing asking price, to the Canada Customs folks. I had a bill of sale showing the actual purchase price ($800 less than asking), but didn't bring a copy of the Craigslist ad. Canada Customs went online at the border crossing and said that they saw $20K+ prices for a 69 Firebird convertible, questioning my stated purchase price. I did have a copy of the Craigslist ad at home and they finally relented and allowed me to import it. As stated, make sure you have all the paperwork in order BEFORE you get to the border. US Customs want 72 hours to check for stlen vehicles or those involved in crimes (drugs) before permitting export. They won't tell you on the phone whether it's cleared, preferring, I suppose, that you show up (to be arrested) if there's a problem.

Otherwise, it's relatively simple.