4 channel amp on a budget

I was working on getting my boat stereo all dialed in and I am lead to believe my current 4 channel amp is not functioning. Power light is on, audio in is plugged in, etc.. even tested my work on another amp and that one worked.

So I need a 4 channel to power my in boat speakers, the speakers are rated at 60 RMS. Any suggestions for something affordable??

I am currently running 3 amps, one for in boats, one for a single sub and one for towers. Is there a better way to do this with budget in mind? I could always sell off the 2 functioning amps to supplement some cost.

Any ideas or info is greatly appreciated!!