If you are trying to keep costs down, then do as the monkey says and keep the box next to the TV.
There are numerous products on the market for extending the reach of video standards like HDMI but none of them are cheap. If I were going in-wall, I'd consider one of Gefen's solutions:
http://www.gefen.com/kvm/dproductlisting.jsp?listingCategory=Extenders&productType=hdmi