Reddit mentions of Danish Modern

It depends on what you consider cheap. Used options for all of these are available at very reasonable prices, though I don't personally think that the new prices are super high, though I do know of the more expensive books you've probably seen like the Wegner book for closer to a hundred.
http://www.amazon.com/Danish-Modern-Andrew-Hollingsworth/dp/1586858114/ref=sr_1_1?ie=UTF8&qid=1450038421&sr=8-1&keywords=danish+modern

http://www.amazon.com/Eames-Gloria-Koenig/dp/3836560216/ref=sr_1_3?ie=UTF8&qid=1450038421&sr=8-3&keywords=danish+modern

http://www.amazon.com/Mid-Century-Modern-Interiors-Furniture-Details/dp/1840914068/ref=sr_1_4?ie=UTF8&qid=1450038421&sr=8-4&keywords=danish+modern

http://www.amazon.com/Danish-Modern-Beyond-Scandinavian-Heywood-wakefield/dp/0764322168/ref=sr_1_7?ie=UTF8&qid=1450038421&sr=8-7&keywords=danish+modern

This is the one I would get:

http://www.amazon.com/Scandinavian-Modern-Magnus-England/dp/1849754349/ref=sr_1_5?ie=UTF8&qid=1450038421&sr=8-5&keywords=danish+modern