Hi,
I purchased the Firefly-BP (Battery Powered) module from a company
called Grid Connect. You can Google them to find their website on the
Internet.
I purchased an RS232 module from Kronos Robotics (
www.kronosrobotics.com).
It is called the "Easy RS232 Interface Kit". The one I have I purchased several
years ago and the new ones that Kronos currently sells look different due to a
different Printed Circuit Board layout. You can find them listed in the
"Easy Modules" section of their website.
SparkFun Electronics sells some RS232 modules and they can be
found at many of the Hobby Robotics\Electronics websites on
the Internet.