I paired the jacket with White House Black Market's black "legacy tux" pant, which match the jacket's fabric perfectly and which were also on sale (although they are not on sale online). The pants I got look exactly like the ones I linked to online and pictured right, except I don't think they are lightly lined. Originally $98, the pants were on sale for $69.99 and I got them 40% off that price for $41.99.
In total, the suit was $101.98! Again, based on the White House Black Market I shopped at, there are a bunch of these complete suits in random sizes floating around on sale.