I'll bite...
What is the amount of bending (a thousand of an inch?) in what time (a millisecond?) should bend?
Any decently powered home stereo should perform to do tests with a piezoelectric element at audio frequencies. If that is what you want, then you can select a cheap amplifier module and attach a transformer at the output to raise the voltage.
If the bending must hold for long times, nitinol is the way to go, and an adjustable DC power supply can do it instead of an amplifier.
Your post does not tell much of your intentions. More information is needed. What is the input frequency to the amplifier ?