Camo is certainly NOT necessary, but can help, and it's all about YOUR confidence in what your wearing and what you like/need. As far as the game is concerned, in most cases anything you wear that is quiet, and easy to move in, and especially, that it breaks up your outline from the games standpoint. That really is the key.
As far as expense goes....I have some of the really pricey stuff, and I love it. It is designed for hunting, and it is a functional and important piece of my gear. There are times when I want to wear what I know, should the need arise, that it will keep me alive and still do what I need it to. The pricier stuff usually fits in this type of niche.
There are a lot of times, hunting near home, when all I need are jeans, and a cotton plaid shirt to do the job.
Pick your camo with it's use, and the area you plan to hunt in mind, with all the needs you have....there is a lot to choose from and a lot of good products out there anymore.
With regards to expensive camo that is designed for specific needs, it really is no more pricey than other specialty clothing....like ski or mountaineering stuff. And the good stuff generally lasts quite well. But do your homework...that's easy enought to do.
You can find some great deals in the classifieds here, and some good input by the folks here as well.