Should I get an internet range extender or an entirely new router?

I have an approximately 2600 square foot one story house. The problem is, my office is on one side of the house and my bedroom is on the other. My wireless router isn't strong enough to reach all the way across the house. So I can't use my laptop while lying in bed. I do have another desktop in between. Which would be easier and more cost effective, to get an entirely new or additional wireless router, or to get a range extender? And what would be a good one to get? Any more info needed?