How much would a 1953 wiffle ball be worth?

It all depends on the manufacturing year...a bat with a stick Wiffle logo and Made in the USA below was manufactured somewhere between 1982 to the mid 90's and in good condition sell for $10 - $50 depending upon the solidity of the bat, with the vast majority being in the lower range.

Those with just a stick Wiffle without the made in the USA predate this area and in good condition could be worth upwards of $100 to a serious Wiffle ball player.

The older the bat the more solid it is and the less it will warp and get out of shape with use - plus generally they are a little heavier and can hit the ball farther.