There are handhelds and modular satellite radios, both of which use various, speciallized docks (so you can own just one radio and use it in various places that have a dock - car, home, specialized boombox, ect). Examples of modular satellite radios would be the Sportster for Sirius and the Skyfi for XM. Those aren't current models, but you can google them to get an idea. My advice is to get a cheap setup and don't subscribe to any contracts - just pay by the month. Then you won't spend a lot finding out which service you like better.
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Why be a label, be yourself and keep others guessing instead. - Dee_.