<p>I'm not a designer, so I'm looking for some free WPF themes.</p>

<p>Any suggestions?</p>

The only one that I have found (for sale) is
reuxables
. A little pricey, if you ask me, but you do get 9 themes/61 variations.
UPDATE 1:
A WPF Contrib project ... which does have 1
theme
that they never released.
UPDATE 2:
Rudi Grobler (above) just created CodePlex
community
for this ... starting with converted themes he mentions above. See his blog
post
for more info. Way to go Rudi!
UPDATE 3:
As another answer below has mentioned, since this question and my answer were written, the WPF Toolkit has incorporated some free
themes
, in particular, the themes from the Silverlight Toolkit. Rudi's
project
goes a little further and adds several more ... but depending on your situation, the WPF Toolkit might be all you need (and you might be installing it already).