I bought a cassette of the Bee Gees' Spirits Having Flown (which lasted maybe two months before it became unusable). I Also bought the tape of Saturday Night Fever.
On vinyl, the first albums I bought (at a flea market) were Billy Joel's 52nd Street and Kool & the Gang's Ladies Night. I got a vinyl copy of Elton John's first Greatest Hits LP as a Christmas gift in 1974, and wore that thing out inside of a few months.
The first CDs I bought were from BMG. I bought James Ingram's It's Real, Seals & Crofts greatest, and James Taylor's greatest among numerous others (you have to take a whole bunch of them at once upon joining). No rap back then (I was still in the Wactower--and did not have enough CDs to hide any obviously filthy songs).