I bought a new Scorpion battery recently from batterystuff.com. The cost was $55 with free shipping, ordered Sunday night, had it on Wednesday(from Oregon to Michigan). I haven't had it long enough to say anything about its longevity, but , so far it's starting my 650 quicker than the Motobatt it replaced ever did. The Motobatt died after 22 months in my case. I would recommend putting any battery you buy on a charger before use to top it off. They say ready to install and use, but, you don't know how long they sat on a shelf before you got it. My two cents worth. FWIW.
Rick.