Vatican City Medals

Hello - I recently saw this medal on eBay.  I hesitate to pay the asking price because I don't know how the seller determined its value.  Without the benefit of some type of a price guide, like the many that are available for US and World Coins, one has to wonder about fair pricing.  One seller was offended when I questioned about how he/she determined the offering price.  I know that metal content, mintage, rarity and condition are all used to determine the value of coins.  I'm not sure about medals.  Does anybody know if such a guide is available for Vatican City medals? Thank you. 

Always good to check for past sold items.

https://www.acsearch.info/search.html?term=mistruzzi+1960&category=1-2&lot=&date_from=&date_to=&thesaurus=1&images=1&en=1&de=1&fr=1&it=1&es=1&ot=1¤cy=usd&order=0

Hi - Thanks for reading my post.  Yes, it helps to check sold items.  I have done it in the past.  The trouble is that there isn't always an identical item to compare it to.  I found a book that is dedicated to Vatican items.  Of course it may not contain approximate prices.  I would settle for the issue price just to give some idea.