I buy metals direct from metal factors most of the time, and few seem to be on line yet, with those that are tending to be expensive. It seems that your best bet might be to either contact a zinc roofing company and ask if they will sell you some sheet off the roll (if the rolls are wide enough) or to use the old fashioned Yellow Pages or similar to find some local metal factors and give them a call. My local place specialise in stainless and aluminium alloys, but can get pretty much anything you ask for within a day or two. I've found that going in in person, cash in hand, usually gets a better price...................

I just go to the local metal fabricators, they usually have a pile of off cuts leaning against a back wall by the guillotine.

Posted By: JSHarris contact a zinc roofing company and ask if they will sell you some sheet off the roll (if the rolls are wide enough)

Will roofing companies tend to have plain natural zinc though (as opposed to the various pre-patinated varieties that are commonly used)?