The first "extreme metal" band I got into was Cradle of Filth and so I began collecting their albums. I soon got into black metal, Norwegian in particular, and began buying what I could find in stores - Gorgoroth, Dimmu Borgir etc. At the time, stores generally weren't carrying much black metal and if they did the price for a CD would be around $30. Eventually stores began to sell some of the classic albums. CDs are much cheaper now but I remember Burzum's Hvis Lyset Tar Oss album costed me $32 back then.
And actually, a local and independently run shop (who only had a small metal selection) started importing Burzum CDs and for a while, they were selling really well!