There’s your average merchandise: CDs, T-shirts, stickers, maybe buttons for the punk-inclined. But then there’s the distinctive item that Amber Lee Baker and Renee de la Prade have on sale during their shows: “The Accordion Babes Album & Pin-up Calendar.”

“It was Renee’s idea,” Baker said. “A friend of hers saw some hot pictures that she had taken of herself for promotion and said that she should make a calendar.”

De la Prade liked the idea, but didn’t want a whole calendar of herself. Some quick enlistment of female, accordionplaying friends ensued.

“Once one woman said ‘yes,’ it was easy to find the others,” Baker said. Each agreed to a simple proposition: Pose in a pin-up style, with an accordion.

“We printed 1,000 copies and sold out in a month,” she said. “We knew we had a good formula.”

That was three years ago. The version that Baker and de la Prade will bring to Thursday’s show at Istvan Gallery with an adult-themed puppet troupe is the 2011 edition. They’re in the midst of editing the 2012 calendar right now, getting disclosure and release forms signed.

Since it’s the middle of 2011 already, the calendar is currently $10, down from its initial $15. They have some copies left because they printed 4,000 this year.

“We’ll stick with that number until there’s a reason to do more,” Baker said.

But it’s not just a calendar of sexy ladies and their squeezeboxes. Purchasers also get a CD that contains a track of music from each musician-cum-model.

“Since you get a whole album of music and a calendar, it’s a pretty good deal,” Baker said.

The disc represents a variety of accordion music styles, from traditional folk to more modern interpretations. Baker plays her original tunes in a singer/songwriter manner, while de la Prade rocks and rolls. Since the tie-in is the instrument itself and not the particular style of the songs emerging from it, people who otherwise wouldn’t have found out about one another have banded together.

“It’s made a network of women who play accordion. We’ll trade bands and do showcases together,” Baker said.

While they haven’t created a fullfledged festival of all 12 calendar girls — “We haven’t figured that out yet,” she said, logistically or financially — Baker noted that shows between three or four of the artists have happened; she and de la Prade tour together as The Accordion Babes.

As more and more fans get turned on to the accordion, larger shows may become viable.

“Lawrence Welk gave it such a bad name that it became a joke. Now it’s experiencing a resurgence,” Baker said. “We’re really ambassadors of the accordion. We’re trying to get people to realize how awesome it is and get them playing it again.”