Big 12 T-shirts are so last-season.

At Buffs apparel shops across Boulder earlier this week, Pac-12 shirts were being unpacked and embargoed to go on sale Friday, as the University of Colorado makes its official move to the new league.

Meanwhile, Big 12 championship shirts may be in demand at vintage shops and forever treasured in the closets of Buffs fans.

"It's pretty nostalgic," said Regent Steve Bosley, R-Broomfield. "I don't know if they're going to be worth anything, but they're valuable to me."

He said he's eager to buy new Pac-12 apparel to add to his collection.

At T-Galaxy, a CU-themed shop on University Hill, Jen LeFavor unpacked and neatly folded stacks of Buffs shirts detailed with the official Pac-12 trademark. Hanging above her were encased newspaper articles chronicling Buffs victories while they were still in the Big 12.

LeFavor, a CU senior, is looking forward to snapping up a black-and-gold T-shirt with the Pac-12 logo on it Friday when the shirts officially go on sale.

Store manager Nina Razo flipped through a folder of T-shirt proofs the shop was expecting to arrive Friday.

"This is going to be the hottest seller," she said, pointing to a design that features images of all the helmets in the Pac-12, overlaid on a gridiron.

She expects a shirt that has the Buffs' 2011 football schedule printed on the back will also go fast.

As for Buffs shirts prominently featuring the Big 12 logo, she said sales increased when CU announced last year that it would be making the league switch. One in particular says "Twelve teams, one love" and features all the teams that were in the Big 12.

At Where the Buffalo Roam on Pearl Street, manager Paula Johansen said the store received two dozen hats with the Pac-12 logo on them that immediately sold out. The store had been taking names from customers who wanted the hats, and employees called the fans when they arrived.

Other stores across the city were expecting shipments later this summer. The CU Bookstore has been taking pre-orders online for Pac-12 shirts.

Kane Stanley, a sales associate at Goldmine Vintage on Pearl Street, said he expects fans will attach nostalgia to the Big 12, so the older T-shirts might have some appeal.

"We carry a lot of old championship shirts, but we wouldn't consider something from 2010 'vintage'," he said. "The older CU Buffs shirts are good sellers."