You're not meant to have that much at that point. That amount is more to show how much a slave costs rather than actually be something the player can afford
and yet theres a path for sucessfuly buying her and letting her go, where all the other slaves are just "oops ya missed it" this one can be actually bought, and wdym by that point? Isnt there no time limit, what would stop some weirdo from going to the fight club 40 times to make the 80k