Transcript for LA's surplus of ultra-lux mansions leads to agents getting extremely creative
Reporter: It is a wild night in Beverly hills. music pumpin' on the dance floor. Exotic pool side performances. Hey! Reporter: And an epic game of vintage dressup. A little weight to it. Look at that. A golden girl disco. How about it? Reporter: In a walk-in closet almost as big as my apartment. Welcome to the disco drag closet. This is incredible. Reporter: But this Andy warhol-themed bash isn't just for fun, and it is a lot of fun. This event has one goal. Sell this brand-new $15.6 million house. I think a wine and cheese open house is circa like 1990. We never do that. In this market you really want to make your house stand out. You want to keep the buzz going. Reporter: There is a building boom in Los Angeles. Mansion size, with multi-million dollar spec homes springing up all over l.a.'s poshest neighborhoods. Right now there are 60 homes on the market that cost more than $20 million. With so much supply, selling high-end houses is getting competitive. Is this what it takes to sell a mansion now? Well, I don't consider this to be a mansion. I consider this to be a luxury home, but it certainly helps to go ahead and put this kind of effort and thought into the home and into the marketing of the home. Reporter: So this house has only been on the market for five or six hours? Yes. Reporter: If you haven't just tried to put this on the market and see if the buyers come why not try that first before throwing a huge party like this? Well, that's no fun, and buyers have choices. So we wanted to differentiate this house. Reporter: Differentiating is key, with even more luxury homes on the horizon. I'd say in the ten to $20 million range you probably have about 60 or so coming on in the next 18 months, and I would say in the $20 million and up you probably have 30, maybe 40 coming on in the next 18 months. Reporter: Jason Oppenheim and his identical twin Brett are part of the show "Selling sunset." These Los Angeles real estate experts say the market is getting saturated with new construction. There's a surplus of ultra luxury homes. The random developers asking $40 million aren't selling and they shouldn't. That's the big difference now. There's quality. To echo what he's saying, there is a lot of supply, but there's not a lot of great supply. Reporter: Landing a buyer for the high end requires creativity. Some agents are making professionally-produced movies like these, showcasing the life you could lead if you bought the house. Check this place. The finest house on the harbor Reporter: Celebrities are also getting in on the marketing game. When I first saw this in 1990, I also fell under its spell and bought the property. Reporter: Michael Douglas himself narrated this sales video for his 200-acre estate on the Spanish island of my orca. I've put my own mark on the place. Reporter: But now he's ready to part with it for $32.5 million. Now it's time for me to let someone else enjoy the privilege and adventure. Reporter: And if a celebrity spokesperson doesn't entice you to buy, maybe one of the over the top amenities sellers are now offering will help seal the deal. This house in Newport beach, California has a room to grow and smoke marijuana. What are some of the craziest things that you have seen people put into homes? Well, I just saw a $40 million home on the street I used to live on and it has an s&m room, so that's unique. Reporter: Others offer extras that are more mainstream. So he takes us to a drive to one of the properties they're selling. We've arrived. Reporter: That comes with all the bells and whistles and then some. Wine cellar. Yes. And curated with some of the best wine in the world. And that wine comes from the house as well. Reporter: This five bedroom, nine bath, $40 million plus dream home in the Hollywood hills. This is the view that $40 million will get you. The house comes fully furnished, complete with a 175-foot-long pool. This pool wraps around the entire house. Reporter: Its own spa. This is better than a hotel. Your dry sauna, wet sauna. You go get your massage, then your cold plunge and hot plunge all looking over the city. Reporter: And a place to keep a dozen cars that looks more like a museum. It's amazing. Reporter: Nothing is for sure in the real estate market. This 12 bedroom, 20 bath home in bel-air used to be the most expensive home for sale in the U.S. I think people really just realized they want to live in this beautiful environment. It's a spectacular way of life here. Reporter: The house hit the market in 2017 for a whopping $250 million. There was no budget. Everything had to be absolutely the best. Reporter: Included with the house, $30 million worth of incredible cars, seven full-time staff members and a helicopter. Two years later, the house is still for sale with a $100 million price cut. Back at the Andy Warhol house, they are pulling out all the stops to entice buyer, even throwing in five of the artist's iconic paintings. Every painting has a story. Reporter: And the only car he ever owned, this 1974 rolls-royce. Just going for a quick cruise. I'll be back. And you can get this house, all the art and the car for a mere $17.75 million. Reporter: It's a bargain. It's a bargain. It sounds crazy to us, but in this luxury space a lot of the homes we sell are bought with the furniture and the art. It's hard to go to galleries and amass your own collection, so this home comes turn key. Reporter: For those who can afford to live large the party, so to speak, is far from over. For "Nightline," Marci Gonzalez in Los Angeles.
This transcript has been automatically generated and may not be 100% accurate.