Always use Right Stuf for your source of information. Amazon's details section is a joke, because anyone can fill out a corrections form and make stuff up.
Yep, from time to time I even run into "region 0" pirate releases on Amazon.
They really should have a script that triggers a human check anytime someone tries to add a "region 0" entry...
If Rightstuf doesn't list a DVD,
http://www.animenewsnetwork.com -> encyclopedia -> anime -> [first letter] -> [title] -> "DVD (region 1)" might help.
In the case of Tristia DVD:
http://www.animenewsnetwork.com/encyclopedia/releases.php?id=3223"Japanese with English Subtitles (No Dub)"
My Got Anime membership paid for itself almost 5 times over this order. I saved $56. I glad they have a membership program
Lucky you.
My orders consist of 90+% pre-orders and that results in GotAnime discount + coupons not applying to any of my Funimation/Sentai(/Nozomi) pre-order items in my order unless there's a sale on those and unfortunately optimizing my orders for lowest shipping costs + customs fees (both more impactful than GotAnime) doesn't often let me plan my orders during a sale... I personally end up with less than 5% off with GotAnime discount + coupons an probably need 2-3 5-6 item orders just to make the GotAnime membership back. I'm not sure I'll renew my GotAnime membership in october; I guess it depends on how many non-excluded DVD announcements (such as from Discotek) will be on my winter 2013/spring and summer 2014 "to get" list by then...

Does anybody know at which point in time GotAnime applies? (place an order containing a december pre-order in september, then GotAnime expires in october: does Got Anime apply to the order (time of order placement) or not (time of order shipment)?
</rant>