... And I don't mean the one with Whoopi Goldberg.
Cara's building is one of those bits of unrealism just like Doc's 14-story underground complex.
A high-ceilinged brownstone (if that's the proper term for it) in good condition, with a decent view and facing the sun would be worth a fortune in almost any city, unless it was so deep on "the wrong side of the tracks" or in the derelict ex-industrial section that it got no traffic or was like living in a demilitarized zone.
With the open floorplan I've shown, the tall ceilings, the un-bricked-up high windows, the hardwood floors, etc. I could see that building, with an operational coffee shop already installed, being worth close to a million even if it's a bit out of the way- twice or even three times that if it's in an upscale or up-and-coming area.
One would assume, then, that unless Miss Cara is an heiress of some kind (she's not) or a successful small-time drug dealer (also not) or won a substantial lottery (she didn't) in reality she wouldn't really be able to afford that place.
And especially not afford it on the income from a coffee shop that only serves four or five customers a day.
Fortunately, TWB isn't reality.
The nitty-gritty details are more or less unimportant to the storyline, sort of like how it's mostly unimportant how Doc acquired his underground complex. (Or his nuclear missile. Or his scramjet. Or that SR-71. Or his roomful of lightsabers. And so forth. )
So, to kind of handwave it away, first off, the building is in a somewhat low-traffic part of town, in an area they're trying to revitalize with some trendy shops.
Second, the price was cut to fire-sale levels, as the previous owner was up on kitten-juggling charges, and needed money for his bail, legal bills, and kitten-adoption fees.
Third, the city was offering special low-interest loans to people buying in that area, specifically to help entice them into investing there, in the hopes of helping revitalize it.
Fourth, as noted, Miki's parents helped them negotiate good terms of the loan, and Cara's parents loaned her a bit to help on the down payment.
Fifth, Cara had a house previously, with quite a bit of equity, which she sold in order to put together an even bigger down.
And sixth, the building did need some repairs, which ate up some of the cash but also saved some by reducing the purchase price even more. She and Miki also put a bunch of "sweat equity" into the place buy doing a lot of the cleaning and repainting themselves.
So it's not that unrealistic, but yeah, for the view we'll see when the sun comes streaming in those big windows, in real reality, there's no way she should have been able to afford it.
Now, about the "Quicksand" gag- I'm gonna steal and use that.