Was browsing for some reasonable quality trackpants earlier today, and noticed that Uniqlo have just now chucked their sweapants on sale at $29.90 (down from $49.90). Unsure if this is part of their Winter Sale, but they weren't marked down when I checked earlier this morning.
If you buy 2+ pairs, you can use the NEWYOKOSO coupon code to get $10 off (min $50 spend for voucher). Most sizes still available at time of posting.
They also seem to stock a very slightly different style, which is also reduced to the same price
UPDATE: Select sizes and colours back in stock. (At time of posting, Grey: XL, Blue: S, L, XL, XXL, Navy: S, XL, XXL). A few other sizes also restocked for the "slightly different style" linked above.
These are the best trackies ever if you feel the cold. Thicker and longer than the women's ones.