Hm. For $10-$15 your solution would be an ethernet cable. I know, you don't want to run one... but that's the solution that fits in that budget.
For $25-$50, you could get a Wireless Ethernet Bridge... like this TP-Link WA500G. I present this particular one simply because if you shop around, you'll find it fits within that price range. There are others as well that will cost that much or more (Poke about eBay for a Linksys WET54g perhaps). This is a good solution because you configure the device itself to connect to your wireless network. It then passes an internal IP address to the device you connect it to... your TV. Your TV is now on your internal network and within the same subnet as all the other devices on your network... just as if it had a wireless card itself, or as if it was wired directly to your router. I keep one of these handy for when I want to connect client's desktops to my network without having to install driver software. These things will work with any device that has an ethernet port.... game consoles, TVs, DVR boxes... you name it. There are even fancier ones that have 4 ethernet ports on them.
For $55-$100 you could go with a power-line adapter, as has been suggested. For that outlay of cash, you get a pair of special plugs that will turn a segment of your electrical conduits in the walls, into a network segment. There isn't any configuration like you would see with a wireless ethernet bridge. You just plug an ethernet cable into your router, plug the other end of that cable into one of the power line adapters, then plug that power line adapter into the wall. You then plug the other adapter into the wall near the TV, and use a second ethernet cable between the TV and the adapter. The more expensive ones will not take up the wall socket as they come with a power pass-thru, but the ones at the lower end of the price range don't have pass-thru plugs... so in order to use them you would need to be able to give up a wall socket. Can be an elegant solution, but then again, can end up being more expensive than you need it to be.
Does the solution you require have to be free? – Bon Gart – 2012-07-02T23:38:36.290
Not necessarly, it could cost around 10-15$ – Serban Razvan – 2012-07-03T10:01:28.797