My mom offered to pay for our portion of a condo (~400) about 5 years ago. We paid for gas and helped with food.

She did so because it was the last time our whole family would go together with a couple sons going on missions.

We were very appreciative and helped with stuff a lot more that trip. On the other hand, by SIL was whining about everything under the sun (room choice, noise level, etc.). She was clueless to the fact the she doesn't get her little princess way when you don't pay.

Fun times!