[zizzer]

I was talking about adding the sensors to the bluetooth sticker device, that's why it'd add cost.

The sensors in your phone won't help to work out where the sticker is. The bluetooth receiver in it is built to detect signals from any direction, so even if you rotate your phone, that doesn't help to work out which direction the signals are arriving from.

[hmexx]

Don't think you are understanding what I am suggesting.

If you know the movement of the phone, you can determine which direction of movement causes the largest increase in signal strength change. So the app would be basically doing what you do to find something (let me move this way, oh I'm colder, I should go the other way) but at a higher spatial and temporal resolution.