A best bet is the Frederick's of Hollywood Women's Parisian Satin & Lace Corset in Black/Magenta (pictured) or Black/Red for $69 with free shipping via the above coupon. That's $12 off and the lowest total price we could find. It's available in sizes S to XL, although not in all size/color combinations.
Placing a larger order? Frederick's of Hollywood takes $20 off orders of $100 or more or $30 off $150 or more. (The discount is taken in-cart.) Note that this discount doesn't stack with the above coupon; shipping for these orders starts at $15.95.