It's true that for about 50 dollars, you can buy a good wireless router. BUT, after using several routers over the past few years, I've found that the most important factor for me is ability to offer a good signal over distance.
Apple Products ARE expensive, but they WORK , and work well.
The Apple Airport, and Airport Extreme have proven the best in every way I use them, from speed, reliability, and configuration options.
The Airport can be set up (easily) as a repeater, which Is useful when needing extra distance from the main router for example. IN this example, I have a FIOS router in a main building and the Apple Airport in the secondary building OVER 700ft away! (there are no buildings, trees etc. in the way). It allows about 80% of the bandwidth even at that distance with the ability to stream video, and/or reliable downloading of files. I rarely get less than 12-13mbs on a 15mbs connection at that distance. .
This Reply sways a bit from the original question but in my experience, if you are willing to pay the $$, you cannot ~ and likely will not regret purchasing an Apple Airport Extreme.. which I use at my office building, and it easily covers a 4,000 multi-floor, and office configuration. I've had little to no luck using other routers, that give me the same reliability and quality of service.
Problem is, many people struggle with dropping $180 for the Airport Extreme, and then $100 for the Airport. To me though, they are well worth the extra price.
Others have mentioned that your modem may need replacement. Of course you need a reliable connection to start with, so it may be a good idea to check to make sure it is operating at peak promise/performance as well..