Hello sevor, welcome aboard.
The best advice is "Use the Search Button, Luke..."
Type 'clone armor' or something similar and you will find a lot of post about clone armor building.
Beware, finish a clone armor is not an easy task... nor cheap, you will spend more than $1000.
You can see many tutorials on
www.clonetroopers.net and
www.clone-empire.com I learn it from there
If you want to start buying something go to the nearest DIY store and buy:
a heat gun, smooth sandpaper, a Dremel (or any other spinning-cutting tool from your favourite brand) a gas mask (yes, gas mask, not dust mask) and ... some body filler like Bondo if you're in the States or Isopon if you're in UK.
After reading all posts about armor I'm sure you'll know who makes what and you can PM them and start ordering some things.
Oh, forget buying from recasters like the known StarFortressProductions or other scum that usually use e-bay to sell things. Do not buy anything if you're not sure who's the original maker of that piece. Recasters might have props that seems good for the price they ask, but please, understand that supporting rescasters means support the end of creativity.
Regards,
Santiago.