Graphic designer Lydia Leith told the Huffington Post that her hand screen-printed, limited-edition Royal Wedding Sick Bags are "just a bit of fun."
Leith, who said she's not an anti-monarchist, told the website that the idea for the colourful bags started out as a joke item that she planned to sell to family and friends.
"But it seems there is much greater demand," she said.
She said the bags are meant to be an "antidote" to the hysteria surrounding the royal wedding and a lighthearted addition to the range of royal memorabilia already available.
Royal officials recently unveiled a commemorative coin featuring portraits of Prince William and Middleton.
Britain's Royal Mint said the coin, available in gold or silver, went through a "rigorous" approval process before it was released - but some critics panned the design, saying the portraits were far from lifelike.
William's office has also already approved a souvenir tankard, plate and pill box that feature the couple's entwined initials, the prince's coronet emblem and the date of the wedding.
Unofficial, unsanctioned designs like Leith's sick bags are also appearing. One U.K. company unveiled a pair of commemorative gnomes, while another introduced a royal-themed condom.
Publishers are hoping to cash in on the royal love story as well.
At least two comic books telling the tale of the royal romance are scheduled to be released ahead of the wedding.
"There's always been a tradition in this country of comics for girls in which the girl dreams of meeting someone famous and falling in love," said Mike Collins, the artist who did the illustrations for Kate and William: A Very Public Love Story.
"In this case, this is what's happened and it's for real," he said.
With files from The Associated Press