I go to a lot of conferences which include overseas presenters. And yes, they are around the same price, but they aim to make a decent profit. I've also organised conferences in Australia. I know the cost of venues in Sydney. JREF will make a serious profit out of this in my opinion. I would be happy to be proven wrong.
"Profit" is not usually a word that applies towards charities or educational groups. The money made isn't paid to shareholders, as is the case with a corporation, it's used to fund the activities of the organization. TAM Vegas is currently the primary fund-raising activity of the JREF. It doesn't have thousands of dues-paying members, it sells only a few books from its online store. It doesn't have a magazine with ad placement to sell. There are a few paid staff members - Randi, DJ, Jeff, Bart, and some part time or intern positions. They have a very small office in Fort Lauderdale. They put out a quarterly small newsletter for paid members, they administer the challenger (a great deal of paperwork goes on). And so on.
The JREF is trying to expand its outreach and resources to schools, and that takes money. TAM isn't just outreach, it is also funding raising. Why do you wish to be proven wrong - it is a legitimate thing to have fund raising activities. It's not any different that NPR or PBS providing programming, over the air, that people can and do listen to for free, and still needing a way to come up with funding to do those things. As DJ has mentioned, in order to expand, you need to raise funds. Printers won't work for free, and you can't send materials to people without printing them.
I, too, go to conferences that make money, although none of them are 'for profit' but are also fund-raising for the particular organizations. All of them have a place where vendors can rent booths to sell or advertise their products, and some of the participating companies will 'donate' a coffee center or something similar, to take the burden of the cost off of the organization. IIRC, the Vegas hotels charged something like $5 per person per day to supply unlimited coffee. Over three days, that would be an additional $15 per person. It adds up.
I looked up some statistics for DragonCon. They charge $100 per person for four days, but they have over 30,000 people attend, with 1500 unpaid volunteers. Sheer numbers means they have much more money to work with, even at a lower per-person fee. It's a fundamental of scale. If you want to sell stuff, you have to pay to have a booth. And so on. And DC is for-profit. At TAM Vegas, a few people have tables to sell books. At TAM UK, I don't believe there were any tables with stuff for sale, at all. All the money to cover the costs, and return something to JREF for fund-raising, was strictly through the ticket sales.
I don't know how many people are expected to attend TAM Oz, but do the math - how much money should the JREF be 'allowed' to earn for a primary fundraising event? $200K? $100K $50K? Did you have a number in mind?