Since it's the best armor plating you can buy in whole sirius, the high price is reasonable. For most people/ships it's even status symbol, to show their wealth. Same thing for the Battleship scanners, which don't even a have any purpose anymore, since you don't have to buy them when purchasing a battleship. The Cap8 has at least the purpose of giving a +0.2 hull multiplier for almost 500 millions.
And yes, I think it's meant to be that expensive in roleplay, because even if it's just a minor improvement by the stats, it's quite costly to produce it. As if it'd be built with a different material than the Cap7, which is just extremely rare but gives a better protection. And as said, this armor shouldn't be available for everyone, so it's rather a status symbol for those who can pay it.
![[Image: Narcotic.gif]](http://sig.grumpybumpers.com/host/Narcotic.gif)