Many of the ports of call lend themselves to easy DIY sightseeing providing you have done your homework. So if this is how you plan to do things them allow, on average £15/20 each per port and if you think this is too much or too little then do your own addition or subtraction. If you intend to use the ship's excursions then just add up the price and if it is a combination of both then the maths are still the same. I would certainly allow on top of that £200 to cover things that you didn't think of and still have a reserve put aside that you hope not to spend but it is there in case. I hope that makes sense. ... Neil.