Hi Helen,
 
I used bobby pins to hold my foundation and have found they work very well.
They are longer than the "standard" clips sold in beekeeping supply catalogs
and also less expensive.  As far as brands go, I don't have a specific brand.
I try to go to discount stores or large chain drug stores and buy the cheapest
ones they have in the largest quantities available.  Make sure you are buying
bobby pins, not hair pins.  (The hair pins are U shaped, bobby pins are more
like a clip)
 
The bees quickly cover up the bobby pins as they build out the comb.  When you
extract, they are not exposed as they hold the original base so I have not had
problems with them in the extractor.  After the comb is built out, you can
even remove them.  I had an older beekeeper tell me he even reused his bobby
pins.  Now that I thought was a frugal beekeeper!
Good luck.
 
Vickie