Since these are going to be very expensive after you get a couple dozen you should buy them as is needed for Quests and Properties. Since you should be fighting off leveling up as much as possible in iPirates, this should be done at your discretion. If you have available PlayMesh Points then you should use these on Crew members when they get expensive. You should start off with a few PlayMesh Points, but if you want to use a number of these then you can always purchase PlayMesh Points packages. Two Crew members will cost you twenty PlayMesh points, so conserve them when playing iPirates. Make sure to only use the PlayMesh Points on Crew members when you have higher numbers, and if you must use them earlier only use them on money.