1. You can either get $100 off select highly-reviewed Casper mattresses or take 10 percent off of any order when you purchase one. These are two separate deals and to get the former, you'll have to use code GIZMODO. Alternatively, use code LABORDAY to take advantage of the 10 percent off deal. While that doesn't sound like much, 10% means you could be saving anywhere between $100-$240 on both a mattress and another item.