The low throughput you're seeing might be attributed to poor signal strength, Wi-Fi and non-WiFi interference, hidden node collisions or a combination of the above. I would try out the following before changing the router. (I assume your Macbook supports 802.11n mode and you're cable/DSL backhaul is at least 15-18 Mbps).
1. Ensure that you have good Wi-Fi coverage throughout your home. If there is a coverage hole, say in some region in your room, then what you need is a signal repeater to boost the signal strength.
2. Most probably the three 2.4GHz channels (1, 6 and 11) are crowded. You might want to connect to the 5GHz Wi-Fi network (which has more channels ~20, lesser devices and hence relatively less crowded and is free from other interference sources such as microwave ovens, bluetooth etc).
3. Moreover, 802.11n at 5GHz can increase your channel bandwidth from 20MHz to 40MHz to improve throughputs in some scenarios. The availability of a number of free channels at 5GHz can greatly increase your throughput. However, note that the signal strength at 5GHz can be comparatively lesser than 2.4GHz because of higher propagation loss at 5GHz.
4. Moving the router around certainly helps a bit (especially for 802.11n mode of operation where coverage pattern is spiky). If the router has external antennas, try placing them in different configurations and check Wi-Fi performance.
5. Finally, try logging to the router settings page (usually typing 192.168.1.1 in any browser should get you there) and check the transmit power, channel number and RTS threshold settings.
a. The transmit power should be set to the maximum per regulations (which usually is the case).
b. Channel number (at 2.4/5GHz) should be set to the least congested channel for higher throughput. However, channel 6 at 2.4GHz is the default setting on most routers and people rarely make changes to it. So setting it to channel 1 or 11 should help at 2.4GHz. Or if there is an "Auto" option for channel selection, you can try that too. At 5GHz, you can again try different channels and choose the one that gives you the best performance.
c. You could also set RTS threshold (default value is 2347) to 500 and check for improvement. This usually helps in preventing frame collisions between hidden devices in your Wi-Fi network.
If all of the above doesn't seem to help, then you may want to re-consider buying a different router.