Doom was released end of '93. In 1992 most of us were in the 286 -> 386 upgrade wave and a 486-33 was easily at $2.5k+ ($5.5k in today's terms). The 486 DX2 66 was a good choice even 1994-1996.
I think it was 1994. It was a loaded 486 with the best 17" CRT monitor money could buy at the time. I think he spent over $7000.