https://smile.amazon.com/gp/product/B01M260BAN/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1
This might be a comparable alternative... Its an all in one solution. You're probably looking into expanding and adding batteries, though, and I'm not sure how easy that would be with this system.
Ya, modularity and expansion are the main reasons I would prefer to build something out rather than an all in one solution.