What is the prefix or suffix for word peddler?

The word peddler doesn't have a specific prefix or suffix. It's a compound word formed by combining the words "peddle" and "er".

* Peddle means to sell goods in a small way, usually by going from place to place.

* -er is a common suffix used to form nouns that refer to a person who does something.

So, peddler literally means "someone who peddles".