promise
word of honor
someone who managers money well
thrifty
when you help with something, especially money
chip in
each month's salary comes, then goes
live paycheck to paycheck
paying, often reluctantly
shell out
under too much money that you owe
drowning in debt
something bought without thought
impulse item
out of this world
astronomical
keep it for when you really need it
save for a rainy day
just can't help buying things
spendthrift/big spender
someone cannot afford something
out of someone's budget
a valueless feature
gimmick
someone who doesn't like to spend money
cheapskate/tightwad
done because it's the right thing
matter of principle