They are used to selling their work to major fashion brands, or seeing it appear in the pages of publications such as The New Yorker magazine.
Now a group of 20 leading Spanish graphic artists are offering their art to help mostly African migrants who get by selling fake designer football shirts, handbags or sunglasses to well-heeled tourists.
Twenty limited edition denim jackets will be used as the prize in a one-off lottery to help Top Manta, an organisation named after the sheets on which many street sellers display their wares.
The association, which is run by former “manteros”, as they are known in Spanish, seeks to help migrants leave this hand-to-mouth life and find steadier jobs.
Among the designs, one jacket shows a black panther, along with the slogan Black Mantas; it is clearly a play on words linked to the black power organisation.
Another jacket shows migrants emerging from the sea. To some it might seem nothing more than a colourful design, but for many street sellers, it is a very real reminder of how they made it to Europe in the first place.
For Aziz Faye, a 36-year-old former fisherman from Senegal, the analogy of the sea brings back memories of how he risked his life twice to begin a new life here in Spain.
In 2007, he sailed in a flimsy boat from Mauritania in western Africa to Tenerife in the Canary Islands.
After eventually reaching Barcelona, he was then deported because he was illegally in Spain.
Seven years later, and after two more attempts, he finally won permission to stay.
“As I was a fisherman, I was used to the sea and how it can be. Luckily for me each time I made the crossing, the sea was calm. I wasn’t frightened,” he told Al Jazeera.
In 2015, he started selling scarves on the street, but wanted to find a way to escape this life.
“People in the street are treated worse than animals. We face such violence from people,” said Faye, a married father of twin boys.
“They find us guilty for selling the goods which they say are illegal. But it is not us who brings in these things. It is easy to blame the poorest people in society.”
Faye helped set up the Top Manta association to help street sellers to get the legal right to work.
Under Spanish law, a migrant from most African states must live in the country for at least three years before they can start the complex process of applying for permission to work legally.
While they wait for the chance to work, they must scratch out a living on the streets.
The presence of the top manta sellers on the streets has prompted controversy in Spain, with some conservative politicians insisting they are menaces who encourage organised crime.
Manuel Valls, the former French prime minister who stood for mayor of Barcelona as a liberal in elections in May, said the top manta sellers were “led and run by an illegal mafia for their own benefit”.
“It is an illegal occupation which occupies public spaces which are for everyone,” he said.
Ada Colau, the left-wing mayor of Barcelona, proposed an amnesty to allows street sellers to work legally.
However, she has since come under political pressure to crack down on the sellers in prominent tourist areas.