Yeah, you've got something much better than some of the more recent pieces for sure. Quality sketches from the sets that are more known for low quality tend to be quite valuable, especially with a character like Spider Man. I think the $400 to $500 BIN or BO is a reasonable start. I don't think it'd go for that but you might be surprised if there's somebody out there that's been waiting for it to show up.
Will 2015 be the year Panini finds Marvin Harrison to sign his NFL's Greatest Signature cards?