There are several suppliers in Paris and I've found them all
welcoming -- whether you're an amateur, student or professional. The
place to go to is the 3rd arrondissement. Rue du Temple is the center
of the jewelry district. I've always done my shopping at the three
stores below, but there are others.
Cookson/CLAL (rue Portefoin?) sells everything. Tools, supplies,
equipment, sheet and wire, etc, chain, findings, casting grain...
(you'll need business papers to be able to buy findings here.)
Budin (rue Pastourelle) sells tools, supplies and equipment and
metals Selfor (near Place de la Republique) sells watchmaking stuff,
packaging, displays, has a smaller selection of tools and supplies
(the basics), and does sell findings in packages. It's more "self
service" than the others.