I would not spend over 400 for a beginner board. And before you worry about advanced tech I would go for an all mountain type of board because you need to get the basics of riding down before you even think of hitting the park.
This is a good website for discounted gear. http://www.the-house.com/snbd.html
As others have said boots are the most important.
I hate rental boards but unless you are sure that snowboarding is something that you will do on a regular basis every season then you should rent in the beginning.