Now through 11:59PM Central on 4/10, receive 20% off sitewide at Sigma, including sale items HERE, with code SIGMA20 at checkout. Free shipping on orders $30+ (free shipping is usually on orders $50+). If you are an international customer, you will receive free shipping on orders $75+ instead of the usual free shipping on orders $150+.
ALSO: I spoke with Nordstrom and it looks like they might be able to price-match this sale IF the item(s) you want are available on both the Nordstrom site HERE AND on the Sigma site HERE. You will need to do a live chat with Nordstrom to confirm this. I cannot guarantee that Nordstrom will price-match for you--I only spoke with one customer service rep, but it's worth a shot if what you want is under $30 and available on both sites. Nordstrom offers free shipping on all orders, no minimum required, and your choice of 3 free samples with all beauty purchases. Nordstrom has two pages of Sigma products on their site (no sale items).
I hope that helps!