Hiya!

Welcome to the family!
Just to add on to what had been mentioned, if you have the skills and time, can also try making certain armor parts from scratch which will greatly reduce the cost further. Our first Vader (Shawn/Chakster) made his except the Helmet from scratch and I bet if given even more time and more/better resources, will look even better. I had read too several time online and in SW Insider how some people with limited skills made most parts themselves, sometime using the simpliest thing found at home or in the nearby stores and it turned out great. I understand that the Malaysian's Vader (Rahmat) also made some parts himself; just before last Month's Movie Carnival Event, he made his own Shin Guards from Sintra he gotten from USA.
As for Soft Parts, yes, it's better to make some locally. 1m of 48" Matte Vinyl/Fake Leather for the Bodysuit cost SGD6-7 at Arab Street or People's Park SC. I do recommand adding in some thin lining to give the Vinyl some "Bulk" and help absorb some of your sweats. For tailoring, as it's Vinyl and has to be quilted, will cost around SGD100-300 depending on the tailor. You will have to ask around for a reliable one as this is a major work and only some knows how to properly sew Vinyl (
Sewing Machine need Walking Foot, lots of newspaper or tissue, once sew, can't modify etc etc).
For Vader's Cape and Tabbards, I discover that it's a "thin" kind of Wool that contrary to its thinness, does have some weight when worn. I have a sample of it from ROTS and had gotten close temporary to the original ESB or ROTJ one.

Heck, the cloth I used for my LOTR Fellowship Cloak seems thin and light, made from a wool-acrylic mix, but when I turned it into the Fellowship Cloak, it was pretty heavy.
Anyway, a real good Vader, just like a Wookie or Wampa, are a "long" term kind of SW Costuming Project as most who do it don't have a Gold Mine so must make or buy the parts gradually. It can stretch from a year of work between RL, Family and Career to several years.
Why most of us buy our parts instead of making them is mostly due to our limited skills, time and resources (
try getting Sintra in Singapore). And getting parts from a
reliable seller will also give us a more "accurate" look to the original plus durability if the armor is treated well.
Good luck!
