What is the maximum + 5 volt current draw for the ultrasonic sensors?
Sorry it took a few days, but I needed to run a workbench test on this one. I took measurements on 5 units, and at 3.3 and 5 volts the highest spike I could get even while triggering a read was 0.01 mA. That said you should be perfectly safe assigning 1 or .5 mA to each Virtuabotix Ultrasonic so you know you will never brown out (because of them at least).
The only real problem with multiple Ultrasonics is triggering them too closely, make sure you trigger each at least 50 ms apart to keep from acting on false readings, and let me know how your project goes.
Founder Virtuabotix LLC