Check your local Radio Shack. I found some rare earth magnets at mine.

I just received an order from K & J Magnets. This thread reminded me of them. I would highly recommend them! They have a lot of useful information about magnets on their website too.

My other hobby is slot cars. Slot cars use a variety of magnets in all sizes, shapes and thicknesses. You can try professormotor.com and go to shop by product>magnets

PMTR1037 are six wafer thin gold magnets that I use for magic. You can stack them to get the right amount of force.

AA

Pack of ten 5/16" dia. by 5/64" thick round magnets at Harbor Freight. I forget the price.. Neodynium and strong. Small size, could be useful for you guys!

As I did not saw this link listed in this thread and as it might interest European magician, here is a link to an online shop with a wide range of neodymium magnets : http://www.supermagnete.fr/eng/

In the past I used these guys http://www.dextermag.com/ you will need an business account. They do have some really high end stuff that is not found elsewhere and can custom mold. Its not cheap and can get very pricey fast but they are very good.

Its also a good source for data sheets and tech specification for all types magnets and I think most of the data is still available on the site just no prices.