If you are already on CEP there is no real reason to up grade to AA; unless you are recording full music (the backing track). For this site and most other singing sites the old CEP is good enough.
But if you have the money to throw away then here is the place to get it for cheap, tho not the latest ver.
http://www.blyapal.com/2003.php?PHPSESSID=f03bbb4d26f6f7aa2c4b1da23d210c34
I am the only one around here who prefer to use KRISTAL rather than Audition; both are freeware.