In Japan, there's an official soundtrack CD for just about every game. They're apparently obsessed with video game music over there, hence the Abe a Go Go soundtrack being sold in Japan and not anywhere else. Bit unfair, but I guess that's the best market; anyway, Japanese goods are only an eBay bid away. Although I'm not sure why Abe's Exoddus (known as Abe99 to them, I think) didn't have a CD.
Although it's not there yet, Abe's Exoddus is listed in the upcoming soundtrack downloads at this website:
http://cubedgz.dynamic-dns.net:8080/gamerips/index.php