Here is a picture of one on e-bay ($75):
http://cgi.ebay.com/VINTAGE-GENUINE-VULCANIZED-FIBRE-BRITISH-SUITCASE-2_W0QQitemZ230087193217QQihZ013QQcategoryZ16085QQcmdZViewItem -It is made out of leather, and has brass hinges, tacks and locks.
http://cgi.ebay.com/Nifty-Vintage-Brown-Leather-Suitcase-LWW-initials_W0QQitemZ130076956803QQihZ003QQcategoryZ16085QQcmdZViewItem ($15) on e-bay, unsure of date 1930's-40's
Here is one made out of aluminum and lined with satin: http://metropolismodern.1stdibs.com/itemdetails.php?id=107536 -Although the price is $500, that could have more to do with its value as a collectible, rather than making an assumption that it was not one an ordinary person would use. Items like suitcases were made out of better materials in the 1930's, since most synthetics did not exist until after WWII.
http://julia.hanovercomputer.com/americana/samo01/cat/0821.jpg -this is a Louis Vitton suitcase made out of leather with brass fittings.