a drop in the ocean	a very small amount that will not have much effect
break even	if a person or business ..., they neither make a profit nor lose money
fall short	not reach a particular level or to fail to achieve sth you were trying to do
fifty-fifty	equal, or in two equal parts
go halves	share the cost of sth with someone so that you each pay 50%
it’s as broad as it’s long	used for saying that you cannot choose between two things or action because the are equal
keep up with the Joneses	try to be as rich, successful, etc as your neighbours
knee-high to a grasshopper	very small, because you were very young
line your pocket(s)	obtain money, especially by acting dishonestly
lock, stock and barrel	including every part of a particular thing, situation, płace, etc
six of one (and) half a dozen of the other	used for saying that two things are equally good or bad
tidy sum/amount	large sum/amount