I don't know how much experience you have, or how much you know about going through with your ODST build, but I included some things I have learned below for your convenience...unless you are already well-aware.
It's a good idea to visit that page for (most) of your ODST needs. Skullcandy Girl and Belakor have created full a full Weta suit from the Landfall shorts, located here. However, there are discrepancies between some parts of that version and the new ODSTs from the latest game. Unless you prefer the comparative simplicity of NZ-TK's helmet (which is still very nice, and I prefer it myself), this is where you'll probably want to get your helmet.
Good luck with your build. Are you going to create a character from the ODST game? Ithica has made a sweet Dare helmet, Team Win Studios has begun a Dutch build (I think), and I'm in the progress of putting together a Romeo. It would be cool if we had the whole gang.