For quick protos, I like AP Circuits (www.apcircuits.com); their price
is (IIRC) about US$48 + $0.68/sq.in for small orders; larger orders
(which I've never done) are about $250+$0.22/sq.in.  For smaller orders,
you get double-sided with plated through holes but no component/solder
mask.  For larger orders, the masks are an extra $60 or so per mask per
order.

For the small-order service, all boards are made in multiples of 2, and
the square-inch price is for the rectangular size of the board assuming
both dimensions are at least 1.5" [i.e. a 1"x12" board would be billed as
a 1.5"x12" board, i.e. 18 sq. inches].  If a board has more than 24 holes
per square inch, there's an extra drilling charge but it's not been all
that much.

Turnaround is fast (get the order to 'em by early morning Monday and
you can have boards by Wednesday!) and I've found the boards to be of
good quality.