Can you buy through your school at a discount? Some places do bulk orders for their fighters, it means not having much say in brand/color, but the price is usually pretty good.
If not, I think the Warrior pads are a good middle of the road compromise between the crap you can find at sports authority and the professional stuff. If you can spend a little more, I'm using the Hyabusa Kenpeki headgear and I love it (I don't use shin pads though, so can't comment on those).
In general, full grain leather > almost anything else for durability and comfort. Body and head protection is generally one size and adjustable, anything with sizing and sold online should have a size chart.