Open up Android Market, search for "Pleco" and tap "Pleco Chinese Dictionary" to instantly download the free basic version of Pleco for Android; you can also download it outside of Android Market by typing pleco.com/getandroid in your device's web browser. (see this page for more detailed instructions on how to install Pleco outside of Android Market).
You can then purchase the add-ons below from inside of the app (in the "Add-ons" tab, accessible via your device's menu button) or from our online store - see this page for more details on how to purchase Pleco.
The easiest / cheapest way to upgrade your copy of Pleco from the basic version is to purchase a bunch of add-ons in a discounted bundle.
Basic Bundle (US $39.95) - includes the NWP English-Chinese Pinyin Dictionary - a good English-Chinese complement to the built-in Pleco Basic Chinese-English dictionary - along with OCR, handwriting, flashcards, stroke order diagrams, text file reader, both audio pronunciation add-ons, and the Hui text-to-speech module.
Professional Bundle (US $79.95) - includes the ABC Chinese-English Comprehensive, ABC English-Chinese, and 21st Century English-Chinese dictionaries, along with the OCR / handwriting / flashcard / stroke order / text file reader / audio pronunciation / Hui TTS add-ons. The ABC English-Chinese is shorter but more learner-friendly (includes Pinyin), the 21st Century dictionary is massive but doesn't include Pinyin (though you can look up the Pinyin / definition for words in its entries by tapping on them).
Each of the feature and dictionary add-ons can also be purchased individually.
Optical Character Recognizer - US $14.95
Handwriting Recognizer - US $14.95, but FREE if you download before June 30th
Flashcard System - US $14.95
Stroke Order Diagrams - $4.95
Text File Reader - US $4.95
Audio Pronunciation (male) - US $4.95
Audio Pronunciation (female) - US $4.95
Text-to-Speech "Hui" (female) - US $4.95
Text-to-Speech "Lulu" (female) - US $4.95
Pocket Oxford Chinese Dictionary - US $9.95.
ABC Chinese-English Comprehensive Dictionary - US $19.95.
ABC English-Chinese Dictionary - US $9.95.
21st Century English-Chinese Dictionary - US $19.95.
NWP English-Chinese Dictionary - US $9.95.
Xiandai Hanyu Guifan Cidian - US $29.95.
Tuttle Learner's Chinese-English Dictionary - US $14.95.
Cheng & Tsui English-Chinese Lexicon of Business Terms - US $9.95.
Gu Hanyu Da Cidian - US $29.95.
Longman Advanced Chinese Dictionary - US $24.95.
Practical Dictionary of Chinese Medicine - US $49.95.
Grand Ricci - US $59.95.
As an experiment, instead of offering educational discount pricing on Android like we do on iPhone/iPod/iPad, we've simply set our Android add-on prices to be somewhere in between the discounted and non-discounted prices on iOS. (except in one or two cases where different license terms allow us to make them a bit cheaper) If we get a lot of complaints about this, we may go back to the old two-price system, but since roughly 2/3 of our users are students or teachers of some sort, we think it may be easier / fairer to just charge everyone the same amount.