I would avoid expensive models of open box boards, in case they don't last long. Most are returned due to memory issues or operator error when configuring and installing. I have 2 newegg open box boards made by asrock, and I've had good luck with both. One was $30 with free shipping, and the other $36 as newegg no longer offers any with the free shipping that I know of. Asrock mailed me 2 backplates for $5 each, and I downloaded the drivers. I suggest 2 identical lower priced boards if you plan on keeping your system at least 3 years. With my spare board and power supply, I can be up and running in 30 minutes or less; most cpus don't fail, it's the board or ps that dies.
I am using an open box msi p35 neo-f and its fine, but i would be very careful about getting an expensive board open box. boards like that are bought by the enthusiasts, which tend to push their hardware... make sure you read all the fine print before you go open box!