Real Time Air Speed or post flight
I cannot believe there is no pressure sensor around that doesn't need at least a 10V power supply...
People that are developping turbine engine control units are using pressure sensors too (to determine engine power output via case pressure), and most turbine controllers run off a 5 or 6 cell nicad battery pack... that is 6 to 7.2 volts...
If you really need 10 volts+ you can put 4 litium cells in series... they would give you a 12 V supply...
Might be expensive though... I don't know how long they'd last at 0.08 Watts...