Outdoor Research makes a bivy one level higher than the one you already selected. I don't know if it would go too far over what you would want to pay, but the Advanced Bivy compared to the Alpine Bivy is a little bit bigger and has a few more comfort features, such as a foot vent, sleeping pad straps, and the two pole design lets you configure the hood in more ways. The only reason I suggest going for the Advanced is because it seems like the reviews for the sleeping bag say that it is a big and bulky bag and in the addition of a sleeping pad and yourself in the bivy it will most likely get a little tight. A little more room might make a world of a difference. Also, the foot vent and the option to put the hood into a "storm" mode will allow you to ventialte the bivy a little bit more if you need to. I found a pretty good site that has more information from a user perspective on the Advanced Bivy ( http://www.kayakacademy.com/catalog/ORAdvBivy.html ). Hope this helps you in your searching. Have fun shopping. 
