OhNoesLawl

The fishing shops in Lumbridge and Catherby also sell 1k feathers each I believe.

During the quest you are required to wear a "sailor hat" to obtain the parts from the delivery dwarf, however when I was doing this quest, I had on a naval hat from the Trouble Brewing minigame and he gave me the parts. Apparently they count as a "sailor hat" as well, I am not aware of any other hats that work other than Naval or the one you obtain during the quest.