WPMU recently published a post on free WordPress themes from premium theme developers.
Theme designers who generally charge for their work, often list a couple of free themes as a showcase. Typically these are hard to find, but this post brings a list of 120 themes together.
Well worth a look.
My only reservation is to check the age of any themes you decide to use – check if it will work with the current WordPress version (and will it be supported in the future).
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