@Michael-Angelo-Go I'm confused about the term "watermark". A watermark is usually semi-transparent text overlaying the entire image in a deliberately garish way to deter art thieves.
It would be incredibly insulting and inappropriate to give this to a paying customer! But it doesn't sound like that's what you're doing: it seems you're talking about your signature. A signature is not the same as a watermark. It's an artistic choice and it's supposed to be a good thing to have the art signed by the artist. Your signature is maybe a bit big (slightly smaller would be more tasteful) but it's not really a watermark and referencing to it as such is depicting it in a really negative light. Giving the option for people to PAY to remove it depicts it in even more of a negative light.
I'm also a bit confused by just HOW MUCH you charge for removing it. It's so expensive that it sounds like that would be the price for a commercial license or some sort of commercial rights. I've never really heard of people paying to have the artist remove their signature, so it may confuse people into believing they purchased commercial rights.
Ultimately if I was a customer this whole thing would turn me off and leave a bad taste in my mouth. I wouldn't have thought twice about the signature before I saw the option for removing it. It makes it sound like you're trying to slap a watermark on a product people are paying for and having them pay an enormous amount of money just for removing it.
Like @lpetiti said, using your work for logos or other things would be illegal to begin with. Building in additional deterrents into your offer just makes the offer less appealing and more confusing. At some point in order to sell your work online, you have to accept that there are inherent risks that you can always 100% protect yourself from. You have to accept that at some point, some people may break the law and steal your designs, and then you'll have to defend your rights and get it taken down. And that you can let this fear stop you from making a living off your own work, or you can decide to enjoy your own work and sell it however you want to sell it, however is most appealing for your customers, despite possible risks.
I had to wrestle with this idea when I opened a shop selling digital only products. I send people high resolution files of my work, with only their word that they'll respect my rules and not use them in any commercial way. Yes it would be easy for someone to buy my product, take the file and turn around and make prints of my art and sell it. But will I let that stop me from selling my own damn art however I want to sell it?
I am so confused by this 
I kinda agree though, the watermark does seem to hurt the image a bit. Maybe make it more subtle or remove altogether?
