For on-line retailer use www.resellerrating.com
to check there ratings. You want to find a store with at least a few hundred reviews and 8 - 8.5 or higher.
I've purchases a lot of video accessories from www.bhphotovideo.com
and have been very happy with their service and quality.
For computer hardware check out www.newegg.com
If in doubt check out the NY Better Business Bureau (if purchasing from a NY store) www.bbbnewyork.org/businessreports
Sometimes you have to enter the address because their url is not listed...
Mike is right-on about the price! You will hear horror stores of no USA warranties and missing upc labels from the boxes (so the retailer gets the mail-in rebate, not you...!) If the price is too good to be true then it's for a reason. When spending a few grand on a camera, $200 - 300 extra for a little piece of mind is worth it..
The GL-2 is a nice camera, you won't be disappointed!