Few things:
First, if you're looking for something "you" it doesn't seem like a hilt inspired by someone elses saber from a movie is the direction to go. (Just sayin')
Second, if there is a hilt that just jumps out at you and says "BAM! I'M AWESOME!" there are a number of ways you can customize it if you have the tools. I usually see custom work done to TCSS hilts rather than SF hilts but it can still be done.
As you've already heard, SF will offer some customization to their hilt designs. Depending on the work being done, they may or may not charge extra.
I'd say just pick your favorite hilt. If there is anything about it that you don't like, think about what you would do to fix it. Then figure out if it's something you or SF could fix.
As for blade length and color, that all just depends on your fighting style and personal preference.
Sorry if that's not entirely helpful. =P
@Naast,
If it's brass powdercoating you're after, I would guess there would be a price to pay for it. If it's actually brass pieces you're looking for, like switches, covertec wheels, kill switches, greeblies or whatever, it almost certainly would cost extra. Brass is more expensive than aluminum.
This is speculation, though. Your best solution is to email This email address is being protected from spambots. You need JavaScript enabled to view it.
with a more specific question on exactly what you want and see if they will charge extra.