"I understand some people want to do something to commemorate Anzac but I become a bit concerned about tastelessness when the commemorations are done on inferior products," he said.
"Most people who want to create something to remember Anzac do it with good intentions but it's not so good if it's done directly for profit-making and there's a large company making a fortune out of it."
The RSA would prefer to work with people who had ideas for commemoration, he said.
"Often people come up with ideas and contact us and in some cases we can work alongside them. That way some of the profits go back to the veterans."
The RSA would make a formal complaint to the Ministry for Culture and Heritage if a poppy was used on a product, on some occasions when the word "Anzac" is used, and for cases it deemed particularly distasteful.
The use of the word "Anzac" on products breaches a law protecting flags, emblems and names.
However, the T-shirts do not breach the act, as they were not made by New Zealand manufacturers or suppliers, meaning New Zealand has no jurisdiction over their trading activity, a Ministry for Culture and Heritage spokeswoman said.
Last year, Woolworths was accused of cashing in on Anzac in its "Fresh in our Memories" social media campaign, which invited Australian consumers to create a profile picture and cover photo for their Facebook page, in memory of past and present servicemen and women, complete with the Woolworths logo.
The supermarket pulled the campaign after consumers branded it "disrespectful", while others flooded social media with their own versions of the Woolworths generated images.
The Herald's attempts to contact Redbubble and Tee Parks for comment were unsuccessful.