When I was in college, I resold high demand systems around the holidays. Some examples of this include the slim PS2, the Nintendo DS, and the XBox 360.
I can tell you from this experience that people pay. The bids are not joke bids. They are people who are willing to pay market rate for high demand items because they want them now. God bless them. Furthermore, you can require payment before purchase.
I did this a couple times for limited edition systems. You just have to wait in line early and get as many as the store will let you.
It's not a tremendous amount of money but if you sell a few $300 systems for 2-3x the original price and you're a college student or such, it adds up fast.
The last time I tried doing it was for the limited edition pikachu 3DS; upon seeing a line of 50+ people in Oakland (most of which probably had the same intention as me), I decided that the gain was not worth it anymore.
I recall my friends doing this for the Wii back in the day. They put in reservations at GameStop and checked daily at various stores. I'd imagine it's the same way. You just have to get lucky sometimes.
I can tell you from this experience that people pay. The bids are not joke bids. They are people who are willing to pay market rate for high demand items because they want them now. God bless them. Furthermore, you can require payment before purchase.