We're now just four days away from Notre Dame's 2009 Commencement. And the controversy surrounding President Obama's invitation to speak at that ceremony continues.

While many are excited, others aren’t happy a pro-choice president will be honored at a Catholic university. For weeks, protesters have displayed graphic images of aborted fetuses, on trucks and even planes in the sky. As you can imagine, this has grown into a pricey operation.

NewsCenter 16 spoke caught up with a couple pro-life organizations that are putting up the money for the protests.

Despite the tough economy, pro-life groups have been able to raise enough cash to keep their message very visible, on a daily basis. In fact, tens of thousands of dollars are being spent on billboards, fuel, mailings, and staff.

While many are offended by the protesters' images, groups like the Center for Bio-Ethical Reform (CBR) believe it's money well spent.

Whether it's by air or by ground-- for about three weeks now-- volunteers and staff with the Center for Bio-Ethical Reform have made the South Bend-Notre Dame area their base camp.

It's well worth it. This is a project that reaches thousands of people. The great thing about the plane is we can go over the heads of the gatekeepers and still reach these people on campus, says Paul Troiani, with the CBR.

So how much does it cost to put that plane and its billboard in the air?

A spokesperson for the CBR says the plane costs about $350/hour to fly-- and with about 19 days of flights, several times a day-- that's costing about $20,000.

And we're told it costs about $500/day to drive each of those billboard trucks for CBR. For security reasons, officials wouldn't disclose how many trucks they have.

“Donations have been pouring in from Catholics all across the nation-- from alumni at Notre Dame who are scandalized that Notre Dame would invite Barack Obama,” says Mark Harrington, a spokesperson with the CBR.

Activist Randall Terry says his group, Stop Obama Notre Dame, spent well over $50,000 and funds are now starting to run low.

“So on one hand, there's a good bit of money being spent, but if you look at the impact around the country and world, it's miniscule,” explains Terry.

Terry says his biggest expense was $38,000 for mailing letters to alumni. He spent another $10,000 to rent an e-mail list for 1.4 million people. Terry also says thousands of dollars have been spent on press release mailings.

“Frankly, I have never seen a project be so successful with so little overhaul funds and with so many volunteers,” says Terry.

Meantime, Notre Dame students have mixed feelings about the messages flying over their campus.

“I feel like it's a little over the top, honestly. I understand why they're doing it and support it, but the way they're doing it is atrocious,” says Notre Dame student, Amanda Bell.

“I was expecting posters, trucks weren't surprising, but to have a plane flying round the clock—really wasn't expecting that,” adds Mihai Iancu, a Notre Dame student.

Randall Terry says the "Roe" of Roe vs. Wade-- the Supreme Court decision that legalized abortion-- will be at Notre Dame this weekend. Randall Terry says Norma McCorvey says she plans to protest Obama’s visit to Notre Dame.

A couple of the protest groups say they plan to stay in South Bend at least a few days past graduation-- to continue to protest as students and parents leave town.

With the President coming to town, officials with CBR say their plane will be grounded by the FAA on Sunday-- and possibly part of Saturday.