You should look on Newegg.com
I own two 1tb Cavalry brand externals, and they have both worked fine for over a year.
Newegg has amazing deals, coupons, extra warranty options, etc. And they have huge amounts of customer reviews on everything.
Honestly though, brands do not mean much. Look at how many reviews the drive has, and how good the reviews are. That should be the main factor in your purchase decision, THEN price.