While supplies last, Newegg has the TP-Link TL-PA210KIT HomePlug AV Powerline Adapter Starter Kit for $29.99 shipped. That's after applying coupon code EMCXVVW262 at checkout. (As with most Newegg coupons, you need to be a newsletter subscriber to use this one. It's free to sign up.)
These really are a plug-and-play solution. Pop one of the adapters into an outlet near your router, then bridge the two with an included Ethernet cable. Then plug the other adapter into a wall outlet near whatever needs Ethernet: TiVo, Blu-ray player, Xbox, etc. Presto! You're done.
This particular kit promises a 900-foot range on your home's electrical circuit and features built-in QoS (quality of service) that promises to help with things that require maximum bandwidth (like, say, streaming video). To that end, it's HomePlug AV-compliant.