Your comment suggests you're looking only for docks with built-in speakers. And while that's understandable from a convenience perspective, from a sound quality and cost perspective you might want to consider separating the functions. For example, I use a pair of portable speakers from iHome (about $40) combined with an iWOW adapter from SRS (another $40.) The sound is really quite amazing for the price. On the other hand, if you really want the charging and audio combined in a single unit, the poster above has the right idea. There are several such systems for about $100 on Amazon.