Someone who sells sewing items might be a seamstress, a needlworker, dressmaker, couturier, garment maker, sewist, artisan, craft-maker, or vendor.
auctioner
Draper
Ironmonger.
A hotdog vendor
A confectioner.
A hatter
It's an old term, probably obsolete by now, but someone who sells fabric is called a mercer.
An agent or representative.
Daniel Studley.
clothier
A confectioner is someone who makes and sells candies and sweets. A chocolatier is someone who specifically makes and sells chocolate.
A spice merchant.