Splash out
Definition 1 of 2
Pro Tip 1/3Occasional Use
Used for special purchases, not everyday shopping. 
I don't usually do this, but I decided to splash out on a designer jacket.
Pro Tip 2/3Luxury Items
Often refers to buying items considered luxurious or indulgent. 
After getting his bonus, he splashed out on a luxury cruise.
Pro Tip 3/3Emotional Impulse
Can imply an impulsive, emotion-driven decision rather than a practical one. 
Feeling down, she splashed out on an expensive spa day.