Well.... only because you asked for constructive feedback, I will post these two recent comps. These two are very representative of what this pennant typically sells for...
https://www.ebay.com/itm/29474967188...p2047675.l2557
and...
https://www.ebay.com/itm/23431611957...p2047675.l2557
$55 and $59 respectively. And here's a similar, but rarer variation that sold for $81 (says "World Champions", as opposed to NL Champs)...
https://www.ebay.com/itm/22479408768...p2047675.l2557
So yes, your asking price is indeed aggressive. Great pennant though. Would be eager to see the rest of the collection, if you care to post it!