Buying a new battery - need advice please

So it turns out my Droid X battery is dead, woke up after a wedding with my battery out and my phone wouldn't turn on. Turns out today one of the people at my table (im a server) had a droid X and i asked him if he would put his battery in my phone and see if it boots up to determine the culprit. Turns out it did and I figured that was the problem. So that brings me to my point, I am not going to buy one through Verizon because it's almost 40 bucks. I found a few sites and was wondering if any of you could tell me how legit they are? Seems like an extremely cheap price for a phone battery and it kind of made me nervous.

http://www.focalprice.com/MB377B/High_Grade_37V_1500mAh_Motorola_BH5X_Lithiumion_Battery_for_Motorola_Droid_A955_Black.html

http://www.all4cellular.com/motorola-bh5x-battery.html

or should I just go through amazon? The prices are all very neglible as they are all very close, I just want the battery asap and for the lowest price. Would any of you buy from these sites or should I just go the safe route through amazon?

Thanks.