I started keeping freshwater tropical fish in my early teen years in the 1950's, and by the mid 60's I had ten or so tanks & had bred a good number of egg-layers including Angels, some Tetras, Bettas, Gouramis and others.
In 1976, when stationed in south-east Asia by my employer - Singapore - I was first introduced to Discus (there were a lot of discus breeders in Singapore even at that time) and got started with a 150 gal tank, which cost about $35. If I remember rightly, and 4" to 5" discus were about $5.- $7. or so.
Have been keeping them on & off ever since.