10 mb I think, was in an IBM 80286 I think. Prior to that I had an 8086 with the basic OS in ROM and floppies to load and run the programs.
Most expensive HD was a Western Digital 3.1Gb, I bought it in 96 or very early 97 for a stunning £380. Worked a treat in my 486 DX2 80. I still have it by the way and the last time I tried it, it still worked.
I am still a keen WD fan to this day and won't buy any other brand now.
EDIT: Can't find the receipt, but it was definately more than £280, technology nowadays is amazingly cheap.