Value of any collectible depends entirely on what a buyer is willing to pay for the item.
When there is a collection buyers, either prospective or historic there is said to be a market.
In this case, unless you have solicited or received a specific offer for the ball, I'm afraid there is no market for a soccer ball signed by a collection of semi-professional indoor soccer players who no longer play at the Spectrum.
Try placing it on eBay to determine it's market value.
Chat with our AI personalities