1. What exactly you mean by range booster?
2. How many devices (wire/wireless) will use the Rnage extended signal?
3. Give a description of the general environment.
The general approach that I take for Coverage issues is the following.
The best way is to lay few CAT6 cables to central locations in the house, install Access Points, or Cable/DSL Routers configured as an Access Points ( Using a Wireless Cable/DSL Router as a Switch with an Access Point - http://www.ezlan.net/router_AP.html
), and connect them to the Main Router.
You do not want/can not/hate/your client hate to lay any Cables.
Start with One affordable Wireless Router that can do WDS (the reason to start with WDS capable Router is that in case you need to add more Wireless WDS hardware the original Router has to support it).
If you are lucky and your environment is conducive to get covered with one Good Wireless Router and you are done.
Buffalo, Linksys, Asus and others have Wireless Routers that can do WDS when flashed with DD-WRT firmware.
Using a Laptop loaded with Wirelessnetview, do a Wireless survey, http://majorgeeks.com/WirelessNetView_d6102.html
According to the signal strength reading, identify spots that have strong signal. and spot with weak, or No signal.
Evaluate how you can cover the space and start placing WDS units.
Additional Wireless Routers in WDS Mode (Wireless Network - Configuration Modes. ) has to be placed in spots were the signal is good about Half way to the dead spots.
How many WDS units are needed? It depends on your specific environment (that is a good the reason to buying WDS units one at the time, try it, and decide on the Next step).
More about the topic (the pages bellow were written a while ago, ignore the specific hardware recommendation just stick to the principle and get current hardware)
Extending Distance - http://www.ezlan.net/Distance.html
Wireless Router as an AP - http://www.ezlan.net/router_AP.html
Wireless Modes - http://www.ezlan.net/Wireless_Modes.html
Wireless Bridging - http://www.ezlan.net/bridging.html