They have had that debate going on for a couple of years now.
Ammonium nitrate and powdered AL works just fine. You have to crush the AN very fine-use a bender, or better yet, a old hand powered coffee grinder works. Just store the AN is a plastic container or it will soak up water. You can use fertilizer but you have to get the stuff that is mostly nitrogen. Cant remeber the mix ratio right now.
AL powder- you have to get the really fine stuff- German. Order it from a fireworks supplier- Normal people can only get 1lb per year which aint much. Or you can get a ball mill (cheap) and make as much as you want.
everything you needNow all the naysayers can chime in and say this won't work, yada, yada. It works just fine and a hell of a lot cheaper. You have to figure out the correct amounts. I use 2 TBS AL to coke bottle (small) of AN.
Somebody on this board also had this recipie last year.
Disclaimer: Dont use any of this information or you may end up killing yourself.