I have made an EL inverter. My design wasn't all that elegant, it used a conventional 240V : 12 V (centre tapped) potted PCB mount transformer in reverse running at about 120 Hz. Simple two transistor astable driving a pair of output transistors. If I were doing it again I'd use a binary divider to generate the complementary drive signals to ensure 50:50 duty cycle and probably run at much higher frequency with a ferrite transformer. The 100 Hz approach works but needs a lot more voltage to push enough current through the EL wire, which is essentially a lossy capacitor.