$12,000
The value of an uncirculated 1999 Silver American Eagle Littleton coin fluctuates based on the market for silver. However, a coin can be expected to have a value of about $40.
Value is $16.85 as of today
The current spot price of silver is $31.71 per ounce, that's the value of this coin.
The value of a Silver Eagle coins is determined by the spot price of silver which right now is $29.23 which would be what your coin is worth, with perhaps another dollar added depending on condition for the coin itself.
A 1999-S Delaware Silver Proof Quarter, certified as a PR-70 Deep Cameo example has a listed retail value of $3,000.00.
Silver sells for around $14/oz
Spot price of silver today is $17.90 buy price for this coin should be about $15.00
The issue price for the proof 1999 Silver Eagle was $24.00.
Painting adds no additional value to the coin. It is still a bullion coin and most of its value is in the silver it contains. The value of the silver changes almost daily. Currently it is about $17.
The spot price of silver right now is $18.50 per ounce. Actual cash value is a little less than spot price at time of sale.
1999 wasn't a really rare issue of the American Silver Eagle bullion coins. Depending on condition, you can most likely add a dollar or two to the value of silver contained in the coin. At the time of writing, sight unseen, I would estimate it to be worth around $30 depending on the grade with the bulk of that value coming from the 1 ounce of silver the coin is made with.
The U.S. Mint does not issue painted coins. The value of one which has been painted is based on the value of the silver in the coin which varies day to day.