Chocolate buttons for making candy

I'm trying to find those chocolate buttons that you use to make candy molds. I've considered using Cadbury buttons, but I'm afraid they might be too creamy and melt more than I would like. I'm using them to make these little pretzels for Christmas. You lay out the little pretzels, put the button in the middle, put them in the oven for a couple of minutes, then when the chocolate starts to turn a little glassy you pull them out and stick M&Ms on them. I'm afraid the Cadbury will melt down through the pretzel which is what I don't want. I know at home you can buy these at Michael's and such. Any ideas?

http://www.cakescookiesandcraftsshop.co.uk/acatalog/Chocolate-Making.html

http://www.cakecraftshop.co.uk/shop/8/469/index.htm

From what I can see, though, a lot of UK folks just use bars of chocolate for their moulds.

I agree that the Cadbury buttons might not work. They do make extra big ones which would probably be better than the normal small ones.

Sorry... not much help I guess!

Thanks. Yeah, my coworkers suggested using a bar or going to some posh bakery to see if they have chocolate. I was hoping to be able to find something local, but I don't think it's going to happen!

Dr. Oetker's chocolate chips aren't bad for making candy.   

Are they bigger, like the size of a pound coin?