Nintendo has had a history of unexplainable supply shortages for in-demand items. (case in point: Amiibo)
http://www.slate.com/articles/health_and_science/science/201...
But consumers with too much money are also helping this "economy" with their purchase decisions. That eBay NES Classic in the parent comment was just sold for $610, more than 10x the retail price, and there are many other offerings. Just take a look at the completed listings and the prices that were paid.
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.
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.
One popular reason may be "boosting" the auction. A common practice is that when someone puts an item for sale as an auction, they will ask a friend to bid on that item when the auction seems to be settling on too low a price. If it happens that after one of such boosts nobody else bids and the friend ends up winning, the friend will just pick "personal collection"/"cash on delivery" as payment/delivery options and never pick the item up; the original owner will wait few days and post the item on an auction again.
See Cialdini's Influence.