If you’re a member of the T-Mobile family and are intrigued by the new, Android-based Sidekick handset, listen up. RadioShack has taken to Twitter to let its customers know that the device will be on store shelves beginning on April 20th. “The new @TMobile Sidekick 4G comes to The Shack on April 20,” reads the post. “Who’s your fav sidekick? Tweet us a pic!#BestSidekickEver.” Announced on March 15th, the Samsung-made horizontal-slider will be priced at $99.99 with a signed 2-year contract. The device will sport a 1GHz Hummingbird processor, 3.5-inch display, 21 Mbps HSPA+ radio, and will run Froyo (Android 2.2) — the Sidekick will be available in matte black or pearl magenta. What was unknown, up to this point, was when the Sidekick would be available for purchase.