Hum, good is all subjective. Some people are fine with using vinyl in place of Leather for example.
I'd suggest reading through a lot of the threads here. There is a 'leather parts' thread for example. Look at all the things people suggest you need to make the leather parts and look up the prices for those leather hides. (leather isn't cheap).
If you notice anyone here has offered to make parts for people (like greeblies, blasters, armor, etc), send them a PM and ask if they are willing to help.
My guess, a really good close to screen accurate costume is going to be well over a thousand dollars. Especially when you rely on other people to make parts for you and you are paying for their time and services.
Are you at least planning to sew and put together a lot of these kits yourself (or have a friend do it at no cost)? I can't imagine how much the cost would skyrocket if you had to rely on someone else to do all the work for you and buy a 'finished' costume.