Would you have agreed if it were a discount instead of an added charge? i.e. Yes is -$3?
Or are you saying the base price remains the same if I opt out, but I would get a $3 discount if I opt in?
I would find scenario #2 a more suitable option. Meaning I'd happily pay the standard price in exchange for opting out, but people who choose to opt in receive a small discount in exchange for their willingness to be used as marketing collateral.
Explicitly charging people to opt out just leaves a bad taste in mouth. And it just makes me thing you are going to nickel and dime me every chance you get.
To be honest, if all the standard painting prices were increased by $3 to roll in the opt out cost, I probably wouldn't care. It's the explicit charging for opting out that rubs me the wrong way and I don't think I've ever encountered it before on any other online transaction I've completed.
A. Happy to pay the full price!
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Q. Price $117. Can we use this as a sample? (No: +$3)
A. No fucking way I'm paying $3 NOT appear in your gallery of samples!
A. Keep the Big Mac. I'm going to get a Whopper from Burger King.
Personally I'd increase the discount to around 10% (raising the base price to compensate) and have "Allow us to use this as a sample" checked by default; but I wonder what % of people have a strong reaction like the OP here.
(Burger King costs $9.99 with no offer.)
And now you buy the Big Mac without making a scene.