I think the dancase a4 got fully funded in 40 minutes and his case cost like $300 USD.
1) Once you buy a s4 mini, you need to buy a bunch of other stuff to even start the build (power button, ribbon cable, pico or hdplex, brick
I think it's great to give people options to customize, but you can probably get more customers if you offer a product that is "ready to go".
Maybe you can include all of these things with the case and make some minor profit from them.
You can always sell a more bare-bones version for the people who want to tinker with their own stuff.
2) Maybe you can sell more accessories
Didn't you mention that you wanted to sell a case stand? Maybe you can sell custom cable harnesses that are the right lengths for the pico/HDplex. Lots of people like having the look, but don't want to do it themselves. You can fetch a premium for such a custom product.
I know the case stand takes design time, but the cabling should be something you can whip up pretty fast, I think.
Maybe you can sell a neoprene travel bag or something?
I really appreciate the way you treat your customers. I'd buy more of your stuff if you sold it 
