Language of Street Vending

I do not know if it has escaped the attention of people but street vendors have a particular language in which they use. Their language is unique to them as they shout out to potential customers for example ", five dollahs ah pound for de tomatoes! Five dollars ah pound allyuh!"

There is also the way in which they display the prices of their produce. Sometimes the spelling is completely wrong and then there are other time where there are only prices. In that case they expect that customers know what they are purchasing and sometimes there are no prices and you have to inquire from the owner. All vendors have this attitude. Some may not be as loud as to shout out their prices for people but wait quietly with their signs or none at all. 

The question comes to mind, is this something that is developed over a period of time from pedaling in the area or did the vendors already have that particular way about them?

I would like to think that it has been adopted over a period of time because they believe it is the best way to advertise their produce or items. This way if a person is passing near their little stall or their car and not paying mind to stop and look at the various stalls but, hear a vendor shouting out the particular price per pound and the item, the consumer would be more inclined to stop and take a look. It might very well be an item that the person wanted.

This was a topic I was not able to find any form of references for. I do not know if I inputted the phrases or words in a wrong order or wrong sentence structure so that I was not able to get any supporting literature. Otherwise than that even if it did not have any supporting literature, I think that this topic is one that should be studied and researched.