Hi Timothy,

Thank you for contacting Mearto with your appraisal inquiry.
The majority of Caniff's auction records are for original comic strips, with only a few personalized cards having been sold at auction in the last 30 years. A few years ago, Heritage Auctions sold a lot of five personalized cards/notes for $2,280 and is the closest recent comparable auction lot to your item:
(https://www.askart.com/auction_records/Milton_Arthur_Caniff/24894/Milton_Arthur_Caniff.aspx?lot=5776563)
Based on the photos and information provided, and subject to examination, this is:

Milton Arthur Caniff (American, 1907 - 1988)
Personalized note card, depicting "Hot Shot Charlie", with a presentation inscription to Ethel Marode, dated 1946
watercolor and ink on card stock
7 5/8 by 4 3/4 inches
CONDITION: tape along upper and lower edges
$400-600*
*represents a fair-market value for auction purposes; retail or asking price may vary.

Please let us know if you have additional items to appraise, and thank you again for using Mearto.