Donald Trump (right) speaks onstage with New Jersey Gov. Chris Christie behind him, in Palm Beach, Florida, March 1, 2016. Luke Sharrett/Bloomberg via Getty Images

The email Donald Trump's campaign sent inviting fans to a rally next week looked familiar: "Meet me in New Jersey!" it urged. But something was different.

"You will need to buy a ticket to get into the rally," it added. The cost: $200.

During the months-long battle for the Republican presidential nomination, rallies staged by Trump, the party's likely candidate in the Nov. 8 election, were free and open to anyone with the stamina to withstand half a day's wait outside and a heady hour packed into a sports stadium or warehouse. Supporters could buy snacks or hats or T-shirts while they waited, but they never had to pay for admission.

The May 19 rally advertised in the email is a fundraiser for New Jersey Gov. Chris Christie, a former presidential rival now working for Trump who, according to news reports, needs to retire debt from his own failed campaign. The emailed invitation to supporters said it will be a fundraiser. It was not clear whether Trump will charge for rallies that are not specifically designated as fundraisers.

The New York billionaire has claimed he was self-funding his campaign and did not need donations. He has financed his offensive in the nominating phase of the race for the White House with loans to himself as well as around $12 million in unsolicited donations from fans.

Now that Trump is pivoting toward the general election, where conventional estimates put the cost of winning at around $1 billion, things are changing.

The move to charge admission for some appearances was just one harbinger of a new relationship between Trump and his fans, many of whom cited their perception of his financial independence as a major factor behind their support. It will test the loyalty of those who have swelled his rallies to capacity, either transforming huge crowds into cash cows or creating more breathing room in the places where he appears.

When asked whether the format of the Christie fundraiser rally would be repeated in the future, Trump's spokeswoman, Hope Hicks, did not comment. "This is a fundraiser for Governor Christie," she said.

Supporters have said Trump's about-face on fundraising does not bother them.

Susan Kihne, a Mandan, North Dakota resident who snagged a ticket to see Trump speak at a petroleum conference later this month decided the $30 it cost her was worth it.

"He's self-funded up until now, so I don't mind supporting him," she said.