REUTERSJoshua 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.