The story makes it look like Levi has no money and that he is spending all he has on Eren, but actually he even has a black card. It seems he just worries for certain things like the way he dresses or gifts for Eren, but when it comes to his house the excuse turns out to be that he just doesn't feel like moving XD
Shingeki no Kyojin dj - Binbou Levi to Bonbon Eren