There is a few ways you can determine the value of the clothing on your own. You can try asking Good Will for reference. They should give you a paper or receipt with the estimated value depending on clothing condition and value. You can also try using the ItsDeductible online tool from TurboTax. See Link below
https://turbotax.intuit.com/tax-tips/charitable-contributions/video-how-to-estimate-the-value-of-clo...
ItsDeductible Online Tool
