For a lousy $500, there are Broncos fans who would sell their soul, not to mention their allegiance to quarterback Peyton Manning and the local NFL team.

Shame on them.

The home-field advantage in the NFL playoffs that Denver has worked all season to secure is being undermined by traitors who live next door to you in Broncos Country.

With Pittsburgh attempting an unfriendly takeover of Sports Authority Field at Mile High, at least 10 percent of the tickets in the 76,125-seat stadium are for sale on the secondary market, there for the taking by Terrible Towel wavers who cheer for the Steelers.

“What’s the point of having season tickets if you sell them, especially to Squealer fans?” Denver realtor Bob Osterheldt said.

You’re not a real Denver fan if you sell your tickets to somebody who wants Pittsburgh to win.

“There’s no light way to put my disgust for those who do that,” said Frank Dardano, a die-hard Broncomaniac.

OK, I get it. The average price on the secondary market for a ticket to the Pittsburgh-Denver showdown is $499.71, according to TiqIQ. This is the United States of America, and our great nation was built on capitalism. If there’s anything we Americans love more than football, it is money.

But what would make a Broncos fan sell out his team? At age 39, Manning needs all the help he can get.

“I can’t use Broncos love to pay the mortgage or buy eggs and bread,” said Lance Baxter of Colorado Springs.

The day that changed Broncomania forever was Jan. 22, 2006. With the AFC championship on the line, it was a glorious winter afternoon, except for one sorry sight. The stadium was awash in a sea of yellow, with towels being waved by Rust Belt escapees who were cheering for the Steelers.

“It was brutal. I’ll never forget walking out in the stadium with Champ (Bailey) as we were going out for DB drills early, before the game. We both looked at each other and said, ‘What is this?’ ” former Denver safety John Lynch told me in 2014. “The problem with the Pittsburgh fans was the Terrible Towels are so visible, so it felt like there were more Steelers fans than Broncos fans. You shouldn’t let that affect you. But I think it affected us.”

The Broncos lost 34-17. As a result, the team adopted ticket-buying policies that made it more difficult for out-of-state fans to acquire seats. The problem now is too many Denver fans have become so jaded that loyalty to the home team seems quaintly outdated.

So let’s give props to the Broncomaniacs who resist the urge to turn a profit by selling their tickets. Here’s a toast to Luke Binder, a Denver native.

There’s a die-hard Steelers fan in the place where Binder works. The offer was tempting: $1,200 for two seats.

But the answer from Binder was a firm: No!

“I’m probably a knucklehead,” Binder said. “But I’m a lifelong Broncos fan and couldn’t bring myself to give up the seats. Get why fans are selling them. I just can’t do it.”

Yes, I believe in a free market. In October, I made a football pilgrimage to my hometown of South Bend, Ind. Paid $297.75 for a sweet seat on the 40-yard line, 31 rows behind the Notre Dame bench. When I sat down next to three guys wearing sweat shirts of the USC Trojans, it made me sick to my stomach.

The Broncos have been established as 2½-point favorites against Pittsburgh. The home-field advantage is generally worth a field goal. If Denver fans give that away, the No. 1 seed in the AFC that the team worked so hard to earn could be flushed away in the name of money.

“You know what you get with money,” Brian Robl of Aurora said. “You don’t know what you get when you go to the game.”

But shouldn’t faith in the home team be worth more than $500?

“I would sell any seat for $500,” Corey Carlson said. “I could watch the game from the beach.”

Talk is cheap. You are what you do.

In Denver, a season-ticket holder who loves money more than the Broncos is not a real fan. Give up your seat to a Steelers fan in return for a handsome sum of cash, and you’re a scalper.

Mark Kiszla: mkiszla@denverpost.com