Cheap marine amps

I know you wanted cheaper, but I really can't say enough about how pleased I was with the Kenwood KAC-1824bt in my bay boat.

Sounds like are going to have the same set up as me. I put 4 of the Kicker 8s in cans and have a rockville audio 1600w 4 channel amp. Each channel gets 100 watts, but still pumps really good sound. Amp was 120 on amazon. You could go up and get the 2400w amp by rockville for 150, just not sure it's worth the extra money or space

I have an NVX VADM4 in my boat, It’s been a great amp for the money. It’s the smaller version of their 4 channel marine rated amps, barely bigger than a dollar bill in length and width. Very powerful, I had never heard of them before but gave the amp a try after seeing a YouTube video saying it was actually underrated as far as rms power. I run it at 2 ohms on 8 speakers and get compliments every time we are at the sand bar or parked somewhere listening to it. On the amplifier dyno video on YouTube it was pushing something like 175 watts rms per channel at 2 ohms. Haven’t had any trouble with it so far, I’ve had it for a little over 2 years now. Took the boat to Lake Ouachita in Arkansas over the summer for a week and ran the radio for 6-8 hours a day and never missed a beat. I normally only run JL stuff but I’m happy with the NVX amp I have.