Edit* I called LG. They are out of stock on the Nitro battery cover and don't know when they will be back in stock. They were $17.xx shipped. I didn't give them my address so where ever you live, that what it'll cost you too.
You can get the Verizon extended battery and cover for the Spectrum online for $49, but they are out of stock too. Damn shame their cover won't fit.