Where do you find a battery replacement for the Sonic Impact i-fusion speaker dock?

I have been looking high and low for a replacement battery for the Sonic Impact iFusion speakers. I lived and died by my portable speakers and it was my FAVORITE accessory for my iPod and when the battery finally went, it was a hard pill to swallow. I finally found a product that is a FANTASTIC replacement. The sound quality is equal, if not better. The portability is incredible, and it's about half the price. I found a great review online and I hope you love it as much as I do!