How do I determine what value an item that I wish to sell has?

[fltrglider]

I have an invitation to the commissioning of the USS Tarawa (CV-40) in the original envelope.  How do I determine a starting price?

[heidilynn0_3]

Hi .. can't find much info that would help.. use search box ..uss commissioning invitation ..scroll on left of result page and click completed items. Found a couple there.