@strawCake - I think the best way to get aloe vera is really from the plant directly. However, if that isn't an option, I think a reputable health food store is the next best thing.
I bought an aloe vera lotion from the regular drugstore last summer. I had a horrible sunburn, and the health food store is kind of far for me. The aloe vera lotion pretty much did nothing for me! I've used aloe vera for sunburns many times before, and it pretty much always helps. The aloe vera lotion was a big disappointment!