Master Replicas did a run of these coins, and you can find them available on eBay, as they are no longer in production at MR. Aside from Disney offered coins, you could also pick them up in a checkers game set.
The MRs are metal and run between $10 and $15
The Disney World coins are also metal and cost $5
The
Disney Store coins are made of plastic and were really cheap.
The Checkers are metal and came in the $25 game set (so, 32 coins for that price)
IMO, the checkers are the best value. They need repainting but they really detail well and end up costing less than $1 each.
The Disney Store coins are nice too. They may be plastic, but weathered up it's impossible to tell without handling them. You might still be able to find them at your local store.
Comparison photos found here: (insert to your browser after the http)
img.photobucket.com/albums/v60/JTampa/potccoinsCOMPARISON.jpg (my post count is "too low to post links".

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