Dear, costly, pricey, valuable, extortionate, priceless.
Expensive ...
Cheap
another word for overpriced is expensive
costly
expensive
Lavish or costly.
"Ancient" is another word for very old.
Some people use the word dear.
another word for very large
An afternoon out is the hint word for another word for a very special afternoon. An afternoon date is another word for the same.
Note that "least expensive" is two words. The least expensive item in our restaurant is the white rice.
The noun form of the word "expensive" is "expense." It refers to the cost or amount of money that is required to pay for something. Another related noun is "expensiveness," which describes the quality of being expensive.