I have not, in the last year, been able to find black leather Recaros in good enough condition to warrant purchase; the few decent seats I have come across on eBay and such surpass $700 a pair. I assume that 3-series seats are just like everything else, and there are six thousand times as many availble for the E36 than the E30. I remember reading some part of a conversation regarding this issue before, but I couldn't find it on BimmerW3rkz.
How hard is it to reverse-engineer E36 seat brackets to fit the E30?
I hope to have better luck finding stock black leather E36 sport seats.