My first music purchases were 7" 45 RPM singles. That format was what teenagers for the most part bought in the early-60’s. Most albums at that time were a hit song and a bunch of filler. The exception to that rule were the albums by The Ventures (and other instrumental---mostly Surf---bands), The Beach Boys, and Paul Revere & The Raisers. At least that was true in my Northern California San Jose-suburb of Cupertino. Of course, the British Invasion changed that, and we for the most part stopped buying singles, the album now being much more than a hit song and filler.
I discovered Goldmine Record Collector’s magazine in late-’76, and learned that there had been a number of non-LP songs that were issued only on the "B" sides of singles. The 7" 45 RPM format became quite collectible in the late-70’s, especially in the genres of Punk, New Wave, and Power Pop. Singles with picture sleeves became commonplace, and added to the fun of collecting.
The first 45 I bought specifically for the "B" side was The Band’s "Ain’t Got No Home". "Get Up Jake" was recorded during the sessions for what became their second, self titled "brown" album, but was not included on it, remaining unreleased until it was stuck on the aforementioned single from the Moondog Matinee album.
Another very collectible single was a mis-pressing of Dylan’s "Positively 4th Street". Instead of that song appearing on the "A" side, in it’s place was an outtake of "Can You Please Crawl Out Your Window". The outtake version is a different recording than the one later released as an "A" side, and remained unavailable anywhere else until the CD reissue craze of the 1990’s.
I have a collection of somewhere around 750 singles, but playing them is a pita. It’s like eating a meal that took you two hours to cook in five minutes!