So for a dumb bluetooth 'puck' say for keeping track of a bicycle or briefcase there is a bluetooth to serial thing on ebay for about $4, $2 for a charge controller, and solder on an old mobile phone battery, everything for under $10 and stick instide a small plastic box with a charge port cut in it.
I think I will order the hardware and publish the .stl files for p3d printing a case once they come.
I would really like a nice QT app rather than the above scripts and a generic launcher.
Sourced from ebay auctions
1 - JY-MCU bluetooth to serial board $1.04(free int'l shipping)
1 - Micro USB 5V 1A Lithium Battery Charging Board $2.37(free int'l shipping)
1 - battery BL-5J (fake) $6.99(free int'l shipping)
1 - (five pack)switches $2.06 (free int'l shipping)
1 - plastic case(I plan to print one)

I imagine that this should be powerful enough for keeping tabs on a bicycle parked on a curb or rack when you are in a coffee shop or restaurant and should run for maybe a week on a charge, the charge board is smart so it wont overcharge the battery and has a microUSB port. The bluetooth gadget is actually a serial adapter so anything you want to serial TTY to can be connected say an arduino with a sound amp and siren or whatever.