WKRP end credits song:
http://www.sitcomsonline.com/sounds/wkrpincincinnatiending.wav
Regarding WKRP re-runs, the way I understand it is there were/are massive problems licensing some of the music they used to play, which explains why there's no massive box set.
EDIT: (i looked it up)
Music licensing
The show was one of the earliest to use extensively contemporary music by big groups and artists of the time such as Foreigner, Pink Floyd, The Who, The Rolling Stones, Queen, The Eagles, Styx, Supertramp, Elvis Presley, The Kinks, Jerry Lee Lewis, Deep Purple, Blondie, KISS, Joe Walsh, Earth, Wind & Fire, The Doors and Talking Heads to name a few . The songs were often tied into the plot of the episode. Music licensing deals cut at the time of production were for a limited amount of time (approximately ten years). In addition, the show was videotaped rather than filmed because it was cheaper to get the rights to rock songs for a taped show.[citation needed] Once the licenses expired, later syndicated versions of the show did not feature the music as first broadcast, but rather generic "sound-alikes" by studio musicians in order to avoid paying additional royalties. In some cases (when the music was playing in the background of a dialogue scene), some of the characters' lines had to be redubbed by sound-alike actors. This was evident in all prints of the show issued since the early 1990s, which included its brief late-1990s run on Nick at Nite.
As a result, production on a WKRP DVD was delayed for years because of the expense of procuring music licenses. It was feared that fans would reject edited versions. Sales of first-season DVD sets of Roseanne and The Cosby Show suggested that viewers prefer original, uncut episodes. However, as was done with many other television series, the DVD release of WKRP in Cincinnati - Season One has much of the music replaced by generic substitutes. In addition, some scenes have been cut or truncated and voice overs used to avoid using unlicensed musical content.[7]