(CNN) Normally, three-year-old used cars drop substantially in value. But last weekend, three 2017 model year Ford GT supercars were sold at auctions in Arizona for an average of $1.2 million apiece, more than double the base sticker price of $450,000.

On Saturday, one Ford GT was sold at an auction by RM Sotheby's for $923,500, while two cars were sold by Barrett-Jackson for $1.2 million and $1.5 million. (The prices include a 10% "buyer's premium" charged by the auction company.)

Why would anyone pay more than triple the sticker price for an almost new car that's still in production?

It's not just about the car itself, although the Ford GT's looks and performance are impressive . It's also about how the car is sold and who gets the chance to buy one.

Creating a hot market

Ford has said it plans to make 1,350 Ford GTs , but so far only 600 are in customers' garages. Even with hundreds of Ford GTs still to be built, though, each one already has a preselected buyer.

close friends. Those buyers were chosen by Ford. Prospective owners had to apply to buy the car, much as if they were applying for a job. Previously demonstrated Ford fandom and a massive social media following definitely helped an applicant's chances. Also, Ford wanted applicants who would take the car out and drive it -- not just lock it up in a slick garage and exhibit it toclose friends.

Selected buyers also had to sign an agreement stipulating, among other things, that they would not sell the car for at least two years. And Ford obviously meant it. When Mecum Auctions sold a 2017 Ford GT for $1.8 million in 2018, Ford sued Mecum. The two companies later settled the suit. Ford has also filed suits against others for early sales.

This Ford GT sold for $1.5 million at Barrett-Jackson's Scottsdale auction, despite the fact that brand new ones are still sellig for a third that price.

The highly selective purchase process and the two-year resale moratorium have meant the market for Ford GTs is even tighter than the low production volume would indicate. Of course, the market will loosen up as more Ford GTs leave the factory and more of those initial buyers pass the two-year mark.

"It's really Ford's first attempt, at least publicly, at limiting the secondary market," said Johnathan Klinger, a spokesman for Hagerty, which provides insurance for classic and collector cars. "Whereas Porsche and Ferrari are well known to do stuff like that, they're a very different company."

In August 2019, Barrett-Jackson sold a 2017 Ford GT in Las Vegas for $1.5 million. RM Sotheby's sold one in California at about the same time that went for $1.2 million. Those were among the first of these cars able to change hands without legal hassles. (Barrett-Jackson also sold two Ford GTs, from the 2017 and 2019 model years, with proceeds going to charity. Those cars went for $2.5 million each, but charity auctions are not indicative of a car's actual value.)

This Ford GT was sold by RM Sotheby's for $923,500.

But there are signs that the market is starting to cool. Earlier this month, at Mecum's Kissimmee auction in Florida, bidding on a Ford GT went to an even $1 million, but the car did not sell because its owner was holding out for more.

"I think the prices on the secondary price market will not go up over the next two years. It'll probably go down," said Karl Brauer, executive editor of Kelley Book and a Ford GT owner. "How much it goes down is much harder to predict."

As cars go, it's a decent investment

There are a number of factors working in the favor of the car's longer term collectible value. First of all, there just never will be very many of them. Even with just 1,350 cars in existence, many of the Ford GT's dedicated owners may never want to sell, although at least a few clearly do.

"I'm a little amazed that so many guys that made that hard cut are selling them with no miles on them," said Craig Jackson, CEO of Barrett-Jackson. Jackson also owns a new Ford GT, as well a previous generation Ford GT, neither of which he plans to ever sell, he said.

The modern Ford GT was created to recall the Ford GT40 racecar that won the Le Mans 24 hour race in the mid-1960s. It may help the new car's value slightly that the Oscar-nominated movie "Ford vs. Ferrari," which recounts the story of the GT40, happens to be in theaters just as a number of new GTs are becoming available for sale, said Klinger.

This is Ford's second modern Ford GT. The last Ford GT, produced for the 2005 and 2006 model years, had a much more "retro" appearance and a big V8 engine. Ford made about 4,000 of them and buyers were not preselected. Even those Ford GTs, though, are still worth at least what they cost when new -- if not somewhat more, according to the Hagerty collector car pricing guide.

The new Ford GT looks sleek like a modern supercar. It's powered by a turbocharged V6 engine. The smaller engine allowed designers to create a compact central body for better aerodynamics.

Ford raced the new car at Le Mans in 2016 on the 50th anniversary of the GT40s first victory there. The new Ford GT finished first in its class.

While Ford GT prices may go down as more enter the market, they almost certainly will never go below what their first buyers paid for them, said Klinger. That makes them a very rare thing among new car purchases: A decent investment.