http://mysteriousbill.weebly.com/airplane-and-miniatures.html
Ertl airplane banks often come in scales useful for 25/28mm gaming. They can be had fairly cheap (I usually pay less than $20 including shipping). The only problems is that they are not all in the same scale with some being too large (1/32 scale). Here is a listing of those in roughly 1/43rd to 1/48th scale.
Lockheed Electra Jr. of the late 30's
http://mysteriousbill.weebly.com/lockheed-model-12-electra-junior.html
1929 Buhl CA6 Spokane Sungod. A strange looking biplane with an enclosed cabin.
http://mysteriousbill.weebly.com/1929-buhl-ca-6-spokane-sun-god.html
Keystone Loening Amphibian. Good for getting you in and out of all kinds of terrain.
http://mysteriousbill.weebly.com/1936-keystone-loening.html
1929 Lockheed Air Express. Strangely the Lockheed Vega, a very similiar plane, is in 1/32 scale.
http://mysteriousbill.weebly.com/1929-lockheed-air-express-airplane.html
Gruman Goose Amphibian. Came out in 1940, so it is a little late for Pulp but it is the same plane as in the Tales of the Gold Monkey TV show.
http://mysteriousbill.weebly.com/1940-grumman-goose-airplane.html
1929 Curtis Robin. Another little known plane, but as the choice of Wrongway Corrigan it warrants a look.
http://mysteriousbill.weebly.com/1929-curtis-robin-airplane.html