I'm thinking of cancelling some plans that I have for a group tour and get together.
Why are you thinking of cancelling the group tour and get together?
They are too expensive and I've been spending too much money lately.
I understand that you're concerned about the cost of these items, but it could be rude to cancel planned activities. Talk to other members of your group that you're concerned with the cost, they may be able to find a way to reduce the cost for you.
So It's fine if I don't have any things planned to spend money on?
Possibly, by talking it out you give them the ability to either chip in or find a cheaper way to do things. If they still want to cancel, at least now they had a say.