There are some on this board that will be able to immediately identify that needle valve. Right now I can't remember the manufacturer, but I do remember several people saying that it's not quite as precise as you'd want (to be able to dial in a specific bubbles-per-second). If I remember correctly, "walking" was also a concern with that needle valve.
But if cash is tight, might not be a bad way to go to get started. $90 for a solenoid + regulator might be about fair, even if you wind up replacing the needle valve.