There are some real stilt fishermen to be found in Sri Lanka, unfortunately, this is a dying trade, if you came to Sri Lanka 20 years ago they were all over the island. However, this has been replaced in a lot of places with people that will pose for you to take a picture for a change of course and this can range from RS100-1000+.
If you find a real stilt fisherman, sit down with them and talk about life in Sri Lanka, they are happy to do that for free, I suggest you do however pay them for their time as you are taking them out of their work for the day.