REUTERS/Joshua Roberts Costco is selling COVID-19 tests that you can take in the comfort of your own home. The test uses saliva samples, which buyers mail to a testing center, receiving results in 24 to 48 hours. The test kit costs $129.99 on Costco.com. The retailer is selling at-home tests that allow customers to test for coronavirus via saliva samples, instead of inserting swabs into their noses for samples. According to test maker P23, the tests are 98% sensitive and 99% specific.