the meaning of "Gimme a ballpark" and "on the high side"

[kjc0123]

What is the meaning of "Gimme a ballpark" and "on the high side" in the following sentences?

 

"Now we're getting somewhere. And you have possession of the family heirloom?"

"That's right." 

"It's here?" 

"Tucked away in Chaney's Self-Storage, on Berkshire Road." 

"What's it worth?" 

"Not nearly as much as my relatives think." 

"Gimme a ballpark."

"Half a million, on the high side." 

[Spacemanbob]

A ballpark figure is a numerical estimate.

example: How much does Alex Rodriguez make per at bat for the Yankees? In the $40,000 ballpark; i.e. about 40 grand.  

[Peter Pedant]

yeah it is a numerical estimate but in round figures.

100, 1000

99and a half could easily be an estimate - of 100, or 110, bu wouldnt be ball park figure

on the high side means that his ball park figure is above the real figure and not below

[jno]

It means 'very approximately'. The idea is that a ballpark is a big place, so the figure guessed could be quite inaccurate; but it suggests the person asking the question has no idea at all what the answer might be and wants a very general guess - $5000? $50,000? $500,000?