Neat find on your 306. Another machine on my ever-expanding want list.
I think your cabinet is older than your machine, it looks a lot like my daughter's cabinet from 1926. Singer did make that basic style for a long time though si it's possible I'm wrong.
Your 306 uses a different needle than most machines, there's a good chance you'll have to order them online. Here's one source:
http://shop.sew-classic.com/206x13-S...eedles_c46.htm
Rodney