Prices vary according to the type of script and the medium they are written in. Some scripts take longer to write than others and when mediums other than inks are used more care needs to be taken. Metallic leaf takes a lot longer to use as a glue, which is difficult to write with, has to be used and left to dry, the metallic leaves are also expensive.

For a silver script I use a Palladium leaf as this does not tarnish.

I do not recommend metallic leaf for envelopes if they are being posted as the leaf is likely to get damaged in transit.