STAPLES (TM) and WHSmith
also you can get magnets from IKEA
You can find that at the mall at any other furniture care stores. And if you have luck you might find them at your nearest Wal-Mart store
There are many places one might go to purchase industrial magnets. In addition to shopping at a home improvement store, one might also find magnets on the Amazon website.
two bar magnets
in the national geographic store they have the equivalent to zen magnets.
Permanent magnets can be purchased from sites such as Magnet Sales and PML India. A permanent magnet is more resistant to factors that would demagnetise it than regular magnets.
One can purchase custom magnets from sites like vista print where they have an affordable prices and free shipping many times. One can also purchase a custom made magnets by looking in yellow book to find a local store that lets one customize magnets.
circular because you can find small circular magnets called "rare earth super magnets" at the store called princess auto
I don't know of any websites that appraise magnets, you could try to take them to an antique store. The best bet would be to list them on ebay with a reserve price and see what you can get for them.
go to a science store
The mineral Magnetite is a natural magnet. It is ferrousoferric oxide withformula Fe3O4.
I am sure if you do a simple Google search, you will be able to find a store that has them. Other than that, why not make your own? Check out http://www.supercheapsigns.com for cheap car magnets. You can design your own, or select one of their templates they have. Quality work and the company is fast in shipping out your order.Hope this helps.
what is a keeper used for