This link compares oil vs propane: http://www.homeconstructionimprovement.com/oil-vs-propane-fo
Another site: http://www.hartandiliff.com/questions_oilvspropane.html
and finally, a fuel calculator : http://www.homeconstructionimprovement.com/oil-vs-propane-fu
I hope these links help, best wishes in Ptown, it is beautiful out that way. Our family used to take our summer vacations there when I was a kid...just beautiful!
Propane works great. Just make sure you have a service so you do not run out while you are away.
You have received some great information from the trulia Pros.
We would like to add that many of the Cape's older homes are seasonal in nature or may have only a partial cellar. In the event that the current heating arrangement is not sufficient, it would be advisable to have a clear understanding of your future options that may be limited by crawl spaces or limited cellar space.
Our recommendation is that you consider not only having a structural inspection but a heating system evaluation by an established HVAC contractor.
Ptown is a fun town and now is a wonderful time to be considering purchase options.