How much power does a strain gauge use?
Strain gauges change their resistance depending on the strain they're subjected to. This means that their current draw will vary depending on the strain. The actual resistance of the gauges will be found on the datasheet, but can vary a lot between different products. For example, this one is 120 ohms, and this one is 10 kohms - clearly a big difference. The overall current depends on your configuration: for example, you could use a Wheatstone bridge or a simple potential divider.