inexpensive high AmpHour 12V rechargeable? Answered

I'm  looking to build a battery-powered speaker system for use on job sites, that will need to be louder than the equipment being used.
For this purpose, I plan on using a tripath amp and some pretty decent speakers I have lying around, but the tough part is power.

I need between 12V and 13.6V, with a relatively high AH rating.

I considered a car battery, but don't want to have to trickle charge.
I considered a Power Wheels battery and charger, but I've been seeing bad reviews on lifespan

Any thoughts?