Let me kick-start this contest with a simple but hard-to-get screenshot:
Pimped - 136.66x (Wikiluck)
(Note: Wikiluck has got no game logs or proper bet history - terrible!)
I agree with @loceff13 that playing with Bonus Buys certainly need a big bankroll and is not recommended for most low budget players.
I have tried playing with Bonus Buys on many various games (fun mode of course) and most of them were and are horribly money-hungry! Big spenders are attracted to this kind of play simply because there's always a chance of getting that max win quickly and easily, despite having to spend and possibly lose a truck full of cash!