My recommendation?
Buy the cheapest linksys routers you can get....the older the better....even buy em used from eBay, or find a friend who replaced his old ones....chances are, they are still useful.
The reason? You can easily upload 3rd party firmware (my favourite is DD-wrt) to turn these cheap routers into powerful and flexible ones.
My current setup at my Inn is a router connected to my modem on the first floor, and then another wireless router on the second floor ( I have three floors) The router on the second floor is programmed to accept the signal from the first router, and rebroadcast it as a repeater using a protocol called "WDS," or wireless distribution system. My wireless works great in all my rooms.
Why use a router, rather than buy a wireless repeater? Because repeaters are not flexible, they do one thing, and one thing only. Routers with the proper firmware can be repeaters, and gateways...not to mention a plethora of other tasks. If you have routers kicking around, install the firmware (you can find instructions here
http://www.dd-wrt.com/wiki/index.php/Installation ) and you'll be flying in no time.
Let me know how it works for ya.