I wasted money on those things.. they work good at first but if you have any humidity going through them they die fast. You can wash them but I don't think they work as well as they did the first use.
DIY carbon filter works just make sure it seals really good.
Otherwise buy a can fan and a huge carbon fillter ($550 USD) ... haven't gone that far yet but it might be the next step because I feel I am outgrowing (no pun :P ) the DIY filter.