We did all excursions through Celebrity (I reviewed our experiences in a topic "Millenium" on these pages if you want to see). They all are expensive. I would focus on the "on your own" excursions. The costs are about the same as transporting yourself and reliable. You can get to the cities and spend depending on what you want to see or do. I see people sharing private group trips looking for people to join in here on this site, I do not know if it is cheaper though.