How difficult would a movement exchange on a san martin captain willard be?

This watch has an NH35 that is messing up out of warranty. I had it regulated, but this didn't fix my issue. I figure that by the time I get down to the cause of the issue with this movement, I will have spent much more than the cost of an entirely new NH35. I consider myself pretty handy, but I have never worked on a watch before. If it would be better to have a pro do it, about how much should I expect to pay? Thanks!