Hello Practica,
I will give you my ideas on valuing such in item. You have what I would call a piece of mid century paper ephemera. It is one of the types of things I deal with. When doing an appraisal of value you need to look for comparables that have sold, in this case it could be difficult to find an exact item, so look for other similar memorabilia featuring Dean Rusk or others that have signed the invitation. Try to find items that have sold and compare, look at yours and all the collector angles it may have. It may have interest in different collecting fields, such as Autographs, White House, Dean Rusk, Political Junkies. The more time you take to research and know your item and promote it the better price you can ask. If you want it to sell price it reasonable. Good Luck.

NOte, I can answer only once but I can edit, so here goes.

As for the collecting fields I mentioned, there may be more if you think outside of the box. I would first use the search engines, looking for information on autographs and there authenticity, Political memorabilia collecting, Also collector clubs, White House ephemera collectors, Search Dean Rusk for additional ideas. Once you start researching you may find other avenues of possibility.

Thanks, Fathertime – can you give me leads about “where” to look for those collectible categories? Not much here on Bonz….

Google Dean Rusk – you’ll probably find a museum or collectors that can help you find more information.