Here's how I got copies of the files I needed: Call, write or email the Central Plains Region of the National Archives.
2312 East Bannister Road
Kansas City, Missouri 64131-3011
You might also try the Archives online ordering.
The file I got were 8 pages each and the cost was $17.00 each. Well worth the money spent. Each file had a photograph, fingerprints, their signature and immigration info and vitals.
Good luck with your research!