Electrical – What kind of amplifier do I need to drive a piezo multi layer ceramic speaker

Be careful with the power ratings of speakers. In the hifi community the power rating is not understood as a value where the speaker performs best. It's understood as a value which, if exceeded breaks the speaker or produces very bad sound results. When picking speakers, you usually multiply the power ratings by 3-4, just to be sure. Before searching for speakers check your amplifiers total output power!
Regarding frequency: 10khz is not enough for a decent music quality. Low quality audio hardware ranges from 50HZ - 16khz.
Decent quality would be 18Hz to 20kHz. Now, a single speaker usually does not perform well over such a wide range. That is why normal speakers are build of a tweeter (for high frequencies) and a woofer (for low frequencies). The woofer plays everything from 50-2khz, for example, the tweeter plays everything else. The signal is split with a high pass, for example.

There is a solution for that problem as well:
Look for a broad band speaker. They are usually ranged from 50Hz - 16kHz. They are not meant to play to loud, though.
One more thing: Keep in mind, that even if a speaker is rated as 180Hz ~ 10kHz it won't perform the same on all these frequencies. Some frequencies will be louder, others are choked. Check the frequency response diagram for the speaker if available.

Another solution:
Try finding PC speakers, somewhere. Maybe even old ones, people dump them everywhere, for no obvious reason. You might know someone who can give you a pair.

The power rating of a speaker indicates the maximum power it can accept without damage. A speaker of an equal or higher power rating than the amplifier is a good idea, otherwise the amplifier at maximum volume is likely to damage the speakers.

The volume will depend on the sensitivity of the speakers. Although sensitivity varies between speakers of different construction, sensitivity is not directly related to a speaker's power rating. Meaning, a 3W speaker will not necessarily sound "louder" than a 6W speaker connected to the same amplifier. There's no particular reason to look for a 3W speaker unless you are trying to cut costs.