I would think that it would be better to know exactly what it is you need to accomplish. Building a 2.4 GHz bidirectional amplifier is not for the faint of heart. Some of the parts are not going to be easy to get, especially the power amp chip. Even the author of the website page to which you refer, says he got his from a Cracker Jack box. PCB layout of striplines at microwave frequencies can be considered partly an art.
Perhaps all you need is a better antenna setup? Maybe one of the "cantenna" designs found all over the web would be all you need. They are cheap, easy to make, and can also be purchased for $20US if you want. It's basically a highly directional Yagi antenna, built around a Pringles potato chip can.