My first Firesign experience was, while being a Marx brothers fanatic, I came across the "Two Places" album (on CD) with Groucho on it. I was fascinated by the Communist joke (Groucho and John instead of Karl and Vladimir), the intrigue of the title, and the low price of $11.99 in a $18.99 CD store.
Ralph Spoilsport's sales pitch was what first hooked me onto the album, but I'll always remember the American Pageant. And, of course, Nick Danger's classic. I've been hooked since, and to this day I still search for vinyl records to expand my library. ("Roller Maidens" is so elusive in Arizona...)