Kingkingy

I'm a designer and am doing a project which will involve creating an artwork with thousands of coins. This questions in two parts: 1. Which coins would be the most cost effective to buy. I need a silver looking coin and a brass looking coin. 2. Where could I purchase these coins. (I'm watching bun pennies on eBay but feel there has got to be a simpler way to purchase) 3. Naturally budget is an issue as with all projects of this type. I really don't want to have to use currency in current circulation. Any thoughts on this matter greatly appreciated.

Great post... 2p and 10p are my fallback options, the more I look into this the more I feel that using current coins is the most sensible option. Would love to use shillings and farthings or bun pennies but getting them together is going to be a thankless task....

Thanks for all the help so far. 19 million Churchill crowns would be great though I think paying for storage on the 18.95m I don't use would wipe me out. I've found London coin auctions and will be contacting them today. Will post up what they say.