be a matter of principle

to be something that you feel you must or must not do, because of your moral principles She couldn’t take the money. It was a matter of principle.

shell out (something) phrasal verb informal
to pay a lot of money for something, especially unwillingly:
If you want the repairs done right, you’ll have to shell out at least $800.
shell out (something) for
She ended up shelling out for two rooms.

have your heart/sights set on something

to want to do something very much, or to be aiming to do something She’s got her heart set on going to France this summer. Don has his sights set on a career in law.

gimmick

gim‧mick /ˈɡɪmɪk/ BrE AmE noun [countable] informal
a trick or something unusual that you do to make people notice someone or something – used to show disapproval ⇨ stunt:
advertising gimmicks

chip in

chip in phrasal verb (see also ↑chip)
1. to interrupt a conversation by saying something that adds more detail
chip in with
Other committee members chipped in with suggestions.
‘It won’t be easy,’ Jeff chipped in.
I’d just like to chip in, Bill, if I might.
2. if each person in a group chips in, they each give a small amount of money so that they can buy something together:
We all chipped in to buy Amy a graduation present.
chip in (with) something
Fifty-two people in the music industry each chipped in $250 apiece.

astronomical

as‧tro‧nom‧i‧cal /ˌæstrəˈnɒmɪkəl◂ $ -ˈnɑː-/ BrE AmE adjective
1. informal astronomical prices, costs etc are extremely high
2. [only before noun] relating to the scientific study of the stars
—astronomically /-kli/ adverb:
astronomically high rents
• • •
THESAURUS
▪ expensive costing a lot of money: an expensive car | Apartments in the city are very expensive. | An underground train system is expensive to build.
▪ high costing a lot of money.You use high about rents/fees/prices/costs. Don’t use expensive with these words: Rents are very high in this area. | Lawyers charge high fees. | the high cost of living in Japan
▪ dear [not before noun] British English spoken expensive compared to the usual price: £3.50 seems rather dear for a cup of coffee.
▪ pricey /ˈpraɪsi/ informal expensive: The clothes are beautiful but pricey.
▪ costly expensive in a way that wastes money: Upgrading the system would be very costly. | They were anxious to avoid a costly legal battle.
▪ cost a fortune informal to be very expensive: The necklace must have cost a fortune!
▪ exorbitant /ɪɡˈzɔːbətənt, ɪɡˈzɔːbɪtənt $ -ɔːr-/ much too expensive: Some accountants charge exorbitant fees.
▪ astronomical astronomical prices, costs, and fees are extremely high: the astronomical cost of developing a new spacecraft | the astronomical prices which some people had paid for their seats | The cost of living is astronomical.
▪ overpriced too expensive and not worth the price: The DVDs were vastly overpriced.
▪ somebody can’t afford something someone does not have enough money to buy or do something: Most people can’t afford to send their children to private schools.

save something for a rainy day

to save something, especially money, for a time when you will need it

spender

spend‧er /ˈspendə $ -ər/ BrE AmE noun [countable]
someone who spends money ⇨ saver:
The new casino hopes to attract big spenders (=people who spend a lot of money).

cheapskate

cheap‧skate /ˈtʃiːpskeɪt/ BrE AmE noun [countable]
[Date: 1800-1900; Origin: cheap + skate 'worthless person' (19-20 centuries)]
informal someone who spends as little money as possible – used to show disapproval:
The cheapskate didn’t even pay for the cab.

thrifty

thrift‧y /ˈθrɪfti/ BrE AmE adjective
using money carefully and wisely SYN economical:
hard-working, thrifty people