Know those records that you insert into a vinyl record player? Basically those, but pirated since a real one costs money when you purchase them at official music retailers. It involves the process of obtaining a legal copy then using wax molds (to recreate a record) and specialized tools (prevent quality loss) duplicating the record. (Also, “Bone Music” existed in the Soviet Union by printing music by using x-ray films).
I doubt that process would’ve been cheaper than buying discs unless you were distributing. Very time consuming too.
Even today LPs aren’t that expensive if it’s not a rare release. ~20€ is a very reasonable price for an album, especially if it’s an independent release or a small label. And you can find a ton of good condition second-hand discs for 5-10€