Here is an article that appeared in RC Soaring Digest Magazine.  While it talks about sailplane radios it is really about upgrading 72 MHz radios to 2.4 GHz.  There are a lot of good used radios out there on 72 MHz.   You can get some super capable radios at a bargain price, but how do you bring them into the 2.4 GHz world, and is the conversion really worth it?   

<div dir="ltr" style="FONT-FAMILY: ; COLOR: ">Upgrading 72 MH Sailplane Radios to 2.4 GHz</div><div dir="ltr" style="FONT-FAMILY: ; COLOR: "><font color="#0066cc">http://www.rcsoaringdigest.com/pdfs/RCSD-2012/RCSD-2012-07.pdf</font></div>