Hi you all,
Thank you for the inputs guys!
My background is not intensive hardware development, but i have designed some boards (Altium designer and Protel) with mixed electronics (analog and digital) mainly for biomedical data acquisition and wireless data transmission. In one of the designs wee needed smaller boards, so i ended up designing 4 layer boards.
The problem is that i only designed prototypes (all the HW assembling, debugging and software was done by me to). I underline prototypes, because that is the real problem in this case, i have no experience with production problems and companys that do assembling etc.
For my market application the arduino and arduino shields already present very good pricing. And i´m very happy with the new arduino board from freetronics that is coming out in April, which already brings Ethernet and mini SD card included 
I want to avoid assembling anything, in reality i just want the work of piling them up, program and closing them in one of the arduino boxs (And ready to go !!).
Basically my plan is to develop and test in the arduino platform.
Probably i will use:
- Arduino Board (maybe the freetronics version)
- Ethernet Shield
- SDcard Shield
- GPRS Shield
- Relay/screwing sockets shields for AI/O and DI/O
- Something Shield so i can add RS485 and 1-Wire support
After doing the upper part, maybe it will be mandatory to redraw small things. So i will do that using has much parts of the usual arduino shields as i can, to avoid as much problems as i can. Then it comes my nightmare, where and how to manage some small production of PCB´s and respective assembling.
So rigth now what i wanted is opinions and solutions on how i could implement this plan with the minimum costs and work.
Maybe some company that already produces for arduino project and does good prices etc... i don´t really know
I will be awaiting for you feedback!! and ingineous solutions
Best regards