I'm too embarrassed to say how many I have.
I never throw them out, as they usually come back into fashion. However, not one has ever been full price. My best bargain was a £100 Per Una coat for £9. For my daughter's Christmas this year, I managed to get her a burgundy duvet coat for £8 in last year's January sales and a matching pair of boots for £7, also at the end of the sales.
I think it's because when I was a child, my school uniform coat also served as my Sunday coat, as my mother couldn't afford to buy both. My friend, on the other hand, had a shiny, purple, maxi raincoat which I lusted after.
My first "best" Coat at 17 was a brown wool maxi coat from C&A, which cost £10. I knitted a yellow cloche hat to go with it and so began the obsession !