AcadieLibre - thanks for your reply.

I've settled on selling Open and Limited edition, but Open are only available in a smaller size, whereas Limited are larger and of course much more expensive. I've also added price scaling i.e. the price of each LE print increases by a percentage after each sale.

You mention steep prices - what do you consider steep, for how many prints in a run and at what size? Are you selling direct or via a website?