Keith,
I've just done two different boards with a bga each, and they are my
first boards that are greater than single layer
. There are a lot of
electrical advantages that you lose if you go to a pin header design.
Honestly, BGA's aren't as hard as everyone thinks they are. Just follow
the recommendations for footprint layout in the datasheet, and use a
manufacturer with 5/5/10 tolerances. I've pinned out well designed
BGA's [~256 pins] on two layers that way [didn't fab that one,
impedances didn't match up], and less well designed BGA's on 4-6
layers.
Get a professional fab house to mount the BGAs for your prototype,
usually costs us ~50 Canadian for bake + mount [on bare boards].
You'll also probably need gold immersion, depending on what the people
who mount your BGA's want.
--David Carne