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.
The real value is $75.00, we just got one for our auction. The intrinsic value varies.
As it's the US team, maybe about 5 - 10 thousands US$
There was no world cup in1984 it was in 1982 and 1986.
depends who signed it
Well it really depends on which 15 players signed the ball. :)
500$
if signed by all players then 150 -200 dollars
The age of when the ball was signed does not determine the value. Supply and demand does. The value of the signature will rely on the popularity of the player that signed the ball, and how often he signed. If there are more collectors than signatures on the market the value will be high. If there are many signatures on the market and a lower number of collectors, a lower value.
25 dollars
100000
If the baseball is "multi-signed", and not "single signed" you would have to name the other players that signed the baseball to get an approximate value.
100