Those case are $150 to $250 from specialty retailers. (Thanks Bauxite)
Some people pay $40 for an after market heatsink+fan, those case come with a passive cooling solution.
So the price is not extravagant for what look like some solid all metal construction + cooling.
I think the case have a clean look, to each his own, but most importantly they have a passive cooling design, using the case side fins.
So zero moving parts, zero noise. and with a modern platform, it will sit at ~20watt idle. (even so my HTPC is in sleep mode 18+ hours a day, unless its Olympics time)
I have been using a HTPC exclusively since 2002, and in the past 10 years this is so far my favorite HTPC case design.
And with the A10, it seem like a perfect combination.
AMD indicated that they will still produce FM2 APU in 2015, so this should be a long lasting HTPC... if you choose to use Trinity guts.