My favorite winter work coat had a zipper go bad.  I went to Zipper Shipper, found the zipper I wanted to buy, and ordered it.  I then had my sister put it in for me.  I am happy with the results. 

IF you know someone who can sew in a zipper,  buying one thru Zipper Shipper is not that expensive - at least I didn't think so.

P.S. I bought the heavy duty zipper, which is what I presume you will want as well.