The phrase "money summer" refers to a period of time during summer where people tend to spend and make a lot of money. It suggests that businesses and individuals experience increased financial activity and opportunities during this season.
A last minute win, with a goal by our (relatively) big money summer signing in front of a packed house was pretty much the perfect start. (throughitalltogether.sbnation.com)
The big money summer signing has been restricted to just 11 league appearances this term. (caughtoffside.com)
Teachers are upset because the city may run out of money this summer. (seethruedu.com)