Remembering that a song at full price on itunes store is $1~ and a monthly subscription to spotify is $13
There is a compounding effect, so buying my library as it is today will cost me about $300~, but that's because I've accumulated 300 songs over the course of about 12 years. (300/12) is about $25 per year.
So the delta is $131... for convenience of being able to listen to a new song once or twice and never again.
The irony of course being that if I ever stop paying, I have access to nothing at all.