Is this the armor you're looking to duplicate?
The vest is a standard crossdraw, very cheap and uterlly worthless for most players, except those on a tight budget and just starting out. As for the other parts, most of these are either custom made (for the movie) or modified sports equipment.
B-B Wars tried something similar to this in developing our Full Body Armor suit, click the picture to view the video.
Attaching the armor pieces isn't all that difficult, finding the right pieces is, and more than likely they'll need to be painted because most sporting goods pads, etc. have logos and striping on them. Some sandpaper, masking tape, and spray paint work wonders.
If you have any further questions, feel free to ask. I'll help anyway I can.