Now, I'm sure this has probably been covered at some point in the past, but I cant seem to find it on the boards.

Looking at the example characters in the BBB, these are supposed to be examples of how a starting character can be made and theoretically should be totally legal. In fact they've errated several of them to make them legal. Then we jump to the rigger character and the vehicles he has. I've looked and looked but I cant find where it says "starting availability of 8 or less unless you're a rigger". Is this explained anywhere?

You're right. The Vehicle Rigger character is not made according to the limits on Starting Characters. He has gear with availability 13 and 12.

GM's do not have to let this character in, even though he is in the book.

/Edit: Now that Rigger3 has dropped the price of the Wasp, the character has enough starting money to also buy a Chrysler-Nissan G12A passenger hovercraft.
/Edit2: He also has enough starting skill points to have one more point in Knowledge Skills.

Well, given that the T-Bird smuggler is practically an archetype in the Denver sourcebook but there isn't a T-Bird that a starting character can have…

~J

I believe the combat decker has over-spent by a fair bit too.

Although a no-no in canon rules, it makes sense for a GM to allow that one piece of character defining gear or cyberware; as long as it's not Move-by-Wire or a SSBN. If it's worth it to a player, they should be allowed their monofilament whip or T-Bird, paying more though.

Defining gear is good. I would probably allow a player something rare such-as a laser weapon, a monofilament whip, or a Tactical Computer if they asked nicely and had a reason to have it (and the character wasn't already twinked to the 8th world and back).

Actually: MBW-4 is on the list of stuff I might allow (at alpha, or maybe beta grade) as long as the player payed a lot for it (45 points or so on resources should cover it). It has huge disadvantages and makes for an interesting character theme. Cyberzombies are not on my allowed list though.