I bought my first set of Armor when I was 16 years old. It was FX armor and was a kit. I had a blast building it! Then I noticed that the armor and helmet were way too big for me. I'm 5'11 115 lbs. Tall and skinny.
I later sold the FX armor and purchased a more screen accurate armor and helmet.
I'm now 19 years old. The more movie accurate armor fits me the best with out a ton of modifications.
If you have the money, buy a set of armor and helmet! It's fun!