Woot has them for $50 right now. http://www.woot.com/

Edit: Amazon, too. http://www.amazon.com/Roku-2500R-HD-Streaming-Player/dp/B007KEZMX4?tag=dealswoot-20 The Amazon one is only 720p, though.

Some ideas:

• A multitool. Not sure this particular one is any good or not, but Leatherman is a good brand.
• Cast iron dutch oven
• A Roku
• Some decent headphones

A lot of video games and "grown-up" board games are in the $30-$50 price range too, if your in-laws play.