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?