I doubt you will ever see this many different offered in a lot? The item "439 Different Space FDC First Day Covers 1960s-1980s Apollo Skylab Satellites +" is in sale since Monday, April 2, 2018.
This item is in the category "Stamps\United States\Covers\Event Covers\Space". The seller is "fadads" and is located in Belleville, Michigan. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, Sweden, South Korea, Indonesia, Taiwan, South africa, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, Mexico, New Zealand, Singapore, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Bahrain, Croatia, Malaysia, Chile, Colombia, Costa rica, Panama, Trinidad and tobago, Guatemala, Honduras, Jamaica, Bangladesh, Bermuda, Brunei darussalam, Iceland, Cambodia, Peru, Viet nam, Uruguay.