Independent Traveler.com has a budget calculator that can help you out. It starts out with having you list airfare and the incidentals that go along with that. It has a spot for airport parking but I would suggest you call the local cab company who can give you an estimate of a trip to the airport from your home. Depending upon the length of the trip, it may be cheaper to take a cab than to park your car. Of course the best money saver is a friend or family member who will take you and pick you up.
Other areas that are calculated for you list room costs, meals, and transportation at the spot of your vacation. Some of the cost of transportation can be estimated more easily by going to the websites of the places you will visit to see what kind of transportation is available and the cost.
Of course you can budget for tours--again check them out online and leave a little wiggle room for something better that might come along.
There is a cruise section with all sorts of things you can budget for. It lists fitness classes there. I'm not fond of spending my cruising time going to fitness classes but if that's your idea of vacation, go for it. Just be sure to budget it in and know that it will be more expensive than the same ones at home.
Some other areas that are included are pet/child care (not at the same place, I hope), visas, internet charges, etc. There may be some other things you think of as well and there's space to add them. With a click you can get a total. If it's sticker shock, go back and see where you can cut. Maybe those spa treatments can wait or you can give each other a massage.
Print out your budget and take it with you. It might be helpful to go over it once in a while and note the changes you make. It could help you stick to it and/or plan the next trip better. A budget can be a good travel companion if you use it.