I am a big believer in reusing wood and try to do this if possible. The environmental and spiritual benefits aside, its also a quality issue as well. The availability of high quality old growth timber is becoming more limited and costly.
I don't know what your wood working skills are but if the right tools are available depending on what style of boom you decide to fabricate it should be a fairly simple and a rewarding project
. You might try to see if the origional construction plans are available for the boom.