Beyond that, almost everyone one makes 8 in and 8 out midi interfaces.
I use 2 Steinberg Midex 8's and they work perfectly (and are made for cubase) they run about $350 new, but I would look on ebay, I got one that was practically brand new for 140.
I had problems with M-audio ones and they really cant take a big midi streams but heres a link;
And if you just want to run 16channels, a 1-in/1-out will do that. You don't need to have every device on it's own midi port when it can be set to 1 channel.