in a pinch for the shirt you can search ebay for "Lucky Brand Jeans LS cotton shirt blue denim stripe button front NWT MSRP $69.50". Ill actually sell you the one I bought, its a large, never worn or washed, for $20 shipped. I ended up with a more accurate shirt.
If your a small or medium, and remember he wears the shirt one size too small in the films, search ebay for "Men's MARC MOTO white blue stripe long sleeve casual button front shirt sz S M L" they are sold out of large, I got the last one. I just cut the shoulder tabs off and replaced the buttons.
To date nobody has got the poncho right. Its either the wrong design pattern, not stitched, impropper material and wrong color. They are also a generic size thats too long. Im 6'3" and am going to have to get a few inches taken off on mine.
Same inadequacies hold true for the hatband and any available holster rig.