DWDM on a single strand

Hi there I was wondering about DWDM equipment on a single strand fiber. What are the capabilities of a "mainstream" DWDM equipment operating on a single strand of fiber on terms of number of channels and reach? By mainstream I mean equipment somewhere in the middle of the price range for DWDM, like a standard offer from a reputable manufacturer. Are the same optical ampifiers used on single strand DWDM and DWDM on a pair? Regards MKS