If you type Cuttlebug Cutting Plates into the search box, it brings up different ones. Since you didn’t specify which plates you need, I don’t know which link to give you. There are several possibilities. They are obviously made by different companies, but they give measurements or say they will fit the Cuttlebug.
You could also see if there is a plastic fabrication company in your area. Before my CB died I had a local guy cut a set of plates for me. I went cheap and didn't have the edges polished and they worked fine. This was several years ago and the price was comparable to buying them.
He also made me a custom stamp block for large background stamps.