You might find excursions from Cannes when you get there or online before you leave. $200 for just Monaco without lunch seems like a lot to me. If Eze was included, for even a bit more, I'd go for it.
I took a Celebrity cruise with my family and we anchored in Villefranche. Since there were seven of us, we booked our own excursions and drivers throughout the trip, which I found on cruisecritic.com. The excursions all recommended on cc, were good.
From Villeranche we were driven to Eze and given time enough to climb to the top and down and then have lunch. From there we drove to Monaco. I was glad that we got there but there really isn't much to it. It's tiny, sparkling clean and has good views. We saw the outside of the palace and the outside of the cathedral, but couldn't go in because there was a ceremony in progress. Then to Monte Carlo, which is beautiful.
It looks like a good trip, I'm sure you'll enjoy it, whether you go to Monaco or not.