So this is about one album per month. The accumulation of music might be slow at the beginning, but I could imagine that 3-4 years in you have quite some collection.
For me, it's not the cost of the albums. It's the delivery system. Many years ago, I ripped my albums (300+), made them enabled on a media server. It was unintuitive and required maintenance. It did not pass the wife-acceptance test.
Spotify just works (for us). It's got almost everything we want to listen to. There are no tasks required for me to listen to anything. IMO, this is worth any extra costs.
I don't normally listen to more than two songs from one album (maybe four at most). Amazon sells individual songs at $1.29, so $11.99 would cover nine songs a month, and after three years you'd have 324 songs. That would be far more than all of my current Spotify playlists (including the ones I never listen to).
So this is about one album per month. The accumulation of music might be slow at the beginning, but I could imagine that 3-4 years in you have quite some collection.