to spend a lot of your own money on sth
DIG (DEEP) IN / INTO YOUR POCKET(S), SAVINGS, ETC.
Meaning of DIG (DEEP) IN / INTO YOUR POCKET(S), SAVINGS, ETC. in English
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005