I need some motor options.

This time of year my PK doesn't see much use unless I'm pulling a trailer around the yard. But I like to crank it at least once a week to keep the battery up. Well, after 3 years of great service, my 1612's crank and rod have decided to part ways. They haven't come apart yet. It started as a light tapping and in less than a minute, was knocking hard enough to feel it in the seat. I shut it off and pushed it into the garage.
I haven't pulled the motor down yet to survey the damage. But in case of the worst, what options do I have? Is a rebuild financially feasible or do I save for a new motor?