best place to buy battery?

[Route66]

My vx6700 gets maybe 20 minutes of batterylife off the charger..so obviously the battery is pretty much toast and im looking at buying a new either 1350 or 1500 mah battery. Is there any other places other then seido to buy one thats less expensive? Dont feel like paying close to $50 for a battery unless theres no other cheaper alternative....

Thank you!