I found a web site with I think is a good price on Odyssey batteries for the DS650. They only list them up to 2003 but I think they stayed the same in the newer years.
They may have good prices for other models too.
Here is what I got:
Odyssey PC545
$85.75 minus 2% coupon code (MBUSA545) good until 11/15/06
Free shipping
Grand total was $84.03

2 year warranty

www.motorcyclebatteriesusa.com

 

The first address didn't work for me so here is another try at it.

Text

 

That seems resonable, i got my odyssey for 85 on ebay best battery you can get. they stay the same throughout the years.

 

Just bought a pc545 online at "The Battery Store" for $69.95, but shipping around $15 of course, still comes out to $85, probably not many other better deals out there, most places want $100+s/h