Audio amplifier modules LM386 IC. Cheaper than building your own.
LM386 Audio Amplifier Module 20 Times 5V-12V Input 10K Adjustable Resistance. Approx $4.00 on eBay.
Onboard LM386 Chip
20 multiplier benefits circuit design
on-board speaker wiring block
on-board 10K variable resistor volume adjust
Onboard power indicator
the chip pin leads, can directly input audio signal
Operating voltage: 5 ~ 12V
board size 41 (mm) x13 (mm)