You could look in to a partnership with ACube. They seem to be willing to invest in manufacturing Amiga products. If you licensed your case design to them then they could use their larger buying power to get the cases made much more cheaply than the small production runs you are talking about. The saving could be passed on to the customer to make the product more desirable, and it could be offered as a bundle with a MiniMig board. You could do a similar thing with a design for the SAM440.
Just an idea :-)
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moto