If you're focusing on the selling aspect:
* Buyer
* Customer
* Consumer
* Patron
If you're focusing on the itinerant/traveling aspect:
* Stationary
* Settled
* Permanent
* Local
If you're focusing on the connotation of being sneaky/dishonest:
* Honest
* Ethical
* Trustworthy
If you're focusing on the connotation of being annoying/persistent:
* Reserved
* Subtle
* Unassuming
Ultimately, the best antonym will depend on the specific context in which you are using the word "peddler."