My full time job is PCB design work and 3D modeling so as a hobby I've made a few customized arduino boards. Over the past few months I've built up a good size schematic and footprint library using the 328P and 23U4 with TQFP and the smaller MLF footprints. So far the cheapest manufacturer I've found is OSHPark which has done a fine job. If you have a project on a breadboard and would like it much smaller on a custom board then I can possibly help.
A few examples are:
h**ps://sites.google.com/site/0miker0/Designing-your-custom-Arduino-Board
a lot of us here in this section of the forum offer the same services. I can be found at www.EmbeddedAT.com. I don't suppose you would like to share your PCB fabrication contacts with us would you. I currently use some Far Eastern fabricators for both up to 5 Prototype boards and over 100 units.
I use OSHPark for my board manufacturing. 13 mil drill via holes and 6 mil width tracks. A 2"x2" two layer board is around $15 + $5 shipping and a 4 layer board that size is around $20 + $5 shipping. The only problem is that the turn around time is a month.
They do a good offer and they have fast shipping too if you need it. I have had boards turned around in 7 working days including shipping to the France for an extra $15 shipping