You might look at this FixnZip replacement. It costs $10, but the plus side is that you don't have to sew anything.
http://www.fixnzip.com/golf-bag-zipper-repair/
Jake in PDX, April 2014
Rain hood needs new zip light vinyl opp 18 inch long.
Ronald gold, February 2011
Try a cobbler. Probably not a Timpsons, more likely an independent. They'll have heavy duty sewing machines.
Robin Carter, August 2007
edit
I can answer this question...
golf bag zipper is broken, can't get anyone to sew it?
