I did a review about the commercialized BSN available in the market, and I found that few of them are commercialized but many research platforms were developed and not commercialized yet.

I can check those systems:

http://www.monicahealthcare.com/index.php

http://www.clearbridgevitalsigns.com/ultra.html

http://www.nonin.com/PulseOximetry/Wireless/Onyx9560-OEM

An option is to use the Arduino - Lilipad platform and the available sensor and actuator nodes. The Lilipad has a circular form pattern with large I/O holes around it that allow integration to clothing. You can either solder the connections, or use special conductive threads to make wired interconnect through the clothing. However, I'd say this is more of a prototyping platform than a commercially available BSN.