["How about 'Sports and Comedy' for $800"] He was on first base, per Abbott and Costello

WHOSWHO

This classic comedy routine’s title question might also describe a reference book’s contents.

This clue references the famous Abbott and Costello routine "Who's on First?" where the comedians hilariously confuse baseball positions with names. The phrase "He was on first base" points to "Who" from the sketch, and the answer "WHOSWHO" plays on that by combining "who's" (the player) with "who" (the question). The "$800" hint ties it to Jeopardy! categories, where "Sports and Comedy" would fit this classic bit.