When me and a friend started making the Blue Spirit mask, we choose a large plastic mask base from Hobby Lobby and then cut the chin to get more of the correct shape. To make the raised parts of the mask (eyes, nose, mouth) we used a pack of Paperclay. We used foamy sheets for the white ear/hair parts.
All in all, it cost about 10 dollars and was super light weight and looked pretty awesome.
I've been looking into the swords; you can find some wooden Dao swords on Ebay for 20 each or so. Only downside: they're pretty heavy.