I have a WRT54GL router that has been running like a champ for years now and I haven't been able to bring myself to replace it. But, I have one area in my house where the signal is weak enough to be unusable on my phone and iffy on the notebook. I'm running DD-WRT on the router and have tried upping the TX power to 100 and that didn't seem to make any difference.
Given the age of the router, I'm thinking of upgrading to a newer N model. My usage is 75% web usage with some file copying/usage (have my files stored on desktop and periodically access wirelessly). I don't do any gaming, file sharing, or streaming. My priority is something that is going to be good and reliable like my current one but help get my range up a little. I would like to keep cost under $100 if possible.
There is a low likelihood that the signal would be that much better from another router. I would spend the $100 for a pair of Powerline adapters and a cheap router that you could configure as an AP in the area of the dead zone, using the powerline adapters in place of running a CAT5e cable to attach the AP to an LAN port of the router. I've done it dozens of times and it works very well for anything short of streaming full HD video.