Hmmmm, I'm going to recommend you spend more than $400, and you do purchase good roof prism binoculars. I birded for years with inexpensive/poor quality binoculars, and consequently went through several pair of them. I found that porro prism binoculars are easy to break or knock out of alignment.
About 25 years ago, I invested in a pair of Swarovski 7x42 SLC binos, and have never regretted it. They are bullet proof, bright, easy to handle and focus. I also carry a personal articles insurance policy on the optics, so they can be replaced if lost stolen, or dropped in the pond. It (the policy) is not expensive. If you have the budget, you won't regret buying high end glass. Ziess and Swarovski are going to give you the best performance, but there are others that are not as expensive.
I recommend relatively low magnification, like 7 or 8 power, and the biggest objective lenses you can get. That will give you the most amount of light without a lot of shake.
Edit: If you can, go into a shop like an Audubon or outdoor store that carries a good selection of brands and types, and see what works best for you. Try them in low light if you can, as that will give you a good feel for what has the best light transmission in the price range you decide upon.
