I don't believe Bongo when she says she works two jobs to support her, her mom, and her sister, but was somehow able to take a month off. What mom would be ok with gambling on her sperg daughters winning a contest by losing a month of income if it meant the three of them might end up homeless? I believe they've been behind on rent before, but their mom doesn't seem irresponsible besides her bad choice in men when she was younger.
I also don't really think she's lying, just that neither of them seems to have enough life experience to understand what things actually cost. It's probably just a few part time retail pity shifts here and there to help with bills and buy her and Bingo crayons and weed. I could be wrong, but their handling of the candy and thinking it was way more than it was makes me think they have trouble with concepts like money.
And Bingo needs to go to a Dr. for her ana-chan malnourishment, that's why she's always cranky and sleeping. She never got those nutrients back from Bongo lol