A friend pointed out that for $70 on Seeedstudio you can purchase a little galvo motor kit containing two galvos with mirrors, a driver board, and power supply. There's an associated datasheet in Chinese that covers the basics of driving it (helpful person in the product page comments translated). You give it -15 V, ground, and 15 V for power. Then apply two -10V to 10 volt analog signals and the galvos will move proportionally.

I went on Amazon and bought a 2 Watt blue laser and laser driver to go with it.