Signatures that have not been properly authenticated could sell at half the market value or less. Two of the most trusted authenticators in the hobby are PSA/DNA and JSA. Check their respective websites for information on how to get your signed football authenticated as well as the fee. The do business through the mail but you can check their show schedule to see if the will be in your area.
it depends if you have a certificate of authenticity (COA)
In perfect condition, and with a certificate of authenticity, dealers ask between $80 and $90 for an autographed picture of Greg Townsend.
You could take it to a professional who studies autographs and get him to confirm that it is the genuine article.
$1,000,000 no joke
Yadier Molina signed baseballs w/ certificate of authenticity are valued around $100 retail.
COA is an acronym that stands for Certificate of Authenticity.
Brett Favre was a well known NFL football player. There are specialist online retailers which buy such items, for example Sports Memorabilia providing the seller has a certificate of authenticity. The seller may also choose to sell the item themselves on Amazon or eBay.
Your answer depends on who issued the 'certificate of authenticity'. The certificate may authenticate the design, the metal, or the gem stone.
between two and three hundred
There are many places where one can find an autographed football. One can find an autographed football at popular on the web sources such as eBay and Amazon.
alot
With NO autograph, and in mint condition without a single flaw, that card is worth 50 cents. Autographed, it's worth about $10. If you tried to sell it on eBay with no certificate of authenticity, you'd be lucky to get half of that. Source: Huge memorabilia and card collector