Water features: The property has at least three groundwater springs, one accessible through a cistern in the middle chamber of the cave, one that yields an average of 100 gallons a day that drips into an indoor pond in the front chamber and one near the woods that creates a shallow pond.
During heavy rain, Sleeper said, the property gets as many as 14 waterfalls from the cliffs.
Sleeper and his family are not the first to inhabit the cave. From 1958 to 1985, it was used as a roller-skating rink. It also doubled during those years as a concert venue that hosted Bob Seger, Ted Nugent and Tina Turner, among others, Sleeper said.
The cave is not actually a cave but in fact a former mine. In the early 1900s, two brothers blasted it out of the hillside and sold the sandstone to a glassmaker.
"I personally would not support anybody living in a natural cave," Sleeper said.
Since posting the listing last month, Sleeper said the response has been "overwhelming." His personal Web site has crashed more than once.
One day after it was posted, "I spent 15 hours answering questions on eBay and I just couldn't keep up," he said. "Every time I would answer a question, three more would show up."
He said 10,000 people were watching the auction, which ended today. Another 70 have pre-registered to bid.
At the same time, Sleeper said he is talking with some private investors about lending him the money to stay in his house. But he won't stop the auction until everything is finalized.
"The goal is not notoriety," he added. "The goal is either to finance or sell my house."