Ahhh, I see now. The suggested certification would be something along the lines of:

" has successfully prepared a razor [of this type] to a certified shave ready condition"

as opposed to:

" has prepared this razor [single or one of a batch] to a certified shave ready condition"

In the first case, cost and time would not be an issue for frequent sellers. It would still be a consideration for the seller who is only planning on selling one or a couple of razors.