I have a "Cunning plan" to quote Blackadder... I am going to make several cases and keep two behind; if my mold breaks (eg I drop it) and can't repair, I will get more clay and press it into one of my formed case halves, in layers so it dries as I go. I can then release it from the plastic and I have a replacement mold! (at least, in theory).
khaag - I have no idea how many people will buy my cases. Between my Multi and Mini projects, they have had 34,000 viewings on YouTube, over 31,000 hits on my website (although that is only via the homepage, not repeat visitors), and many thousands of hits on this site as well as thousands of hits on other forums and blogs (from me and others). Possibly around 100,000 in total. If (only taking my website hits and YouTube hits as they come from other sites like Engadget, etc) only 1/10 of 1% buy from me I could sell 65, if 1% buy, 650; or I could get orders for 5 or well over 1,000: who knows. What I do know is that I doubt I will sell more than a couple/few hundred at very most before I stop as otherwise I can't get on with project work!

Each kit is going to be prepared by me and each case mold done and prepared by me; as well as packing and getting posted; that is a lot of time...
It's one of those things that might sell a dozen or hundreds; I have no way to predict; so on that basis, I need to keep my manufacturing small and made to order; by putting a few up on e-bay at a time, when they sell, make more and back on e-bay again. Also, with each kit I will need to source materials, which take a few days to arrive anyway. Just bought 100 tact switches with the rubber contact pads from Hong Kong (useful for the C buttons for my N64 addon project), they will take about a fortnight to arrive; for example. Another issue is the packaging - I have about 12 boxes ready for initial orders, after that I might need to get some specially made (cost and time).
If I knew I was going to sell hundreds I might look into getting them manufactured, however if they only sell in low quantities then the tooling costs and run costs would end up costing me money.
I therefore prefer to keep my operation small, to keep control and also give a decent profit for my time and effort to make it worth my while. I need to sell nine kits before I get my R&D and materials recovered before I even start seeing any profit at all. When my mold breaks and I can't make another then that will be the end of supply; so best idea, if you want one, is to be one of the early buyers!
I have costed the kit, but not disclosing details until I can detail the value for money people will get; a price is immaterial until perceived value is given, ie what you get and what it does and its benefit to you; what I can say though is that my kits will be cheaper than "the alternative" and I will ship anywhere in the world.
UPDATE:
Found this search after a quick Google search:
here
9 x 6 x 4 inches is fine.
Buying two packs of 25 and after postage and tax, will cost £34.04, so 68p each (about 97c). Seems a fair price, and if I don't sell enough case kits, I can use the remainder to ship e-bay items in.
Won't buy them until I need them, also I will need to buy other stuff from them too maybe.
I will also speak to Remploy, they are based in Portsmouth, about 30 miles from where I live as they purely employ disabled people as their workforce to manufacture items; I would prefer to support their work and ethos; however don't know if they will provide what I want (should do, major supplier).