TK's, and most of the 501st and RL Legions don't approve of most commerically "off the shelf" armor and the like. Helmets are another story and with modification are more than acceptable.
E-FX is the reorganized Master Replicas and basically are the new licensed producer of Star Wars prop replicas.
http://web.mac.com/mikeharrison/armor.html
http://www.tk899.com/
Mike does a excellent job of informing the regular guy on all the acronyms and makers of Armor from over the years. He also includes what build best fits the suit for your height, weight, etc. I know some guys buy FX and get a TE, TE2, or ATA helmet to replace the FX helmet. I know that Deckard makes exequistite FX armor and sells a Light edition, which is just the armor with out helmet, then you get the supplies, etc.
What I can say is don't buy commercially available armor, or first check with our Detachment leaders...I know Rubies has Stormtrooper Armor for sale, but it takes a good amount of modification to be acceptable. Part of becoming a Stormtrooper and getting into this hobby is actually doing the build yourself, that's where some of the joy comes when you know you did a kick butt job and that you did it.
The only armor I know comes assembled, obviously cost more would be Trooper Master Armor, or TM armor, also fan casted, one of the best suits in the realm of white armor bar none. I hope to one day get a suit of TM's.
So there are also different varients of Stormtrooper Armor. ANH, ESB and ROTJ, within ANH is the Stunt trooper, and Hero versions. In short the Hero version is more attention to details, bubble lens, and that the holster has 4 rivets, instead of 2 on the stunt. Other than that, they are the same. ESB and ROTJ have different hand plates, and helmets painted a different way, notably the black gloss frown. The interesting note with ROTJ is that the bridge connecting the front and back plates, isn't a cosmetic touch like in ANH and ESB but rather are practical.
http://www.tonybarnett.plus.com/index.html
Tony does a excellent job showing all the little differences between the suits. So do some research learn some surpising facts and then choose what suit best fits your build and what kind of Stormtrooper you want to make, or if you rather go dirty and be a TD, or Sandtrooper!
Then when i bought my playstation 3 in 2006 i was really hyped up for rainbow six vegas, so i combined them and got TheSixHunter, although my current playstation game is GamingLegacy. And if i ever lose someweight, i get a stormtrooper suit, which if you have any suggestions please tell me, and i turn 18 i would love to join you guys sometime! 
Also thanks for welcomes! 
Just let me know bro if you have more questions, and believe me none of them are stupid, especially with this hobby ask first before you do anything, at least until you have a good idea of what your doing!
