I just discovered this wonderful website showcasing Soviet political posters! The Sergo Grigorian Collection is apparently the largest publicly available, private collection of Soviet political posters spanning the entire existence of the USSR, from 1917 to 1991. There are original posters for sale as well as high-quality digital images. The digital images are quite expensive, to say nothing of the authentic, original printed posters. However, there is a nice selection of picture books that are much more affordable. At any rate, you can view the entire collection for free online.
The Proletarian Handbook (Available on Amazon)
Against the Rich (Available on Amazon)
People always have been the foolish victims of deception and self-deception in politics, and they always will be until they have learnt to seek out the interests of some class or other behind all moral, religious, political and social phrases, declarations and promises. – V.I. Lenin