I think the problem here is that you're emotionally invested in this calf and his future, but the potential buyer presumably has more than one option, so is not. You might not like it, but buying and selling like this is a game. Your objective is to get the most you can for your calf, and his objective is to get the calf for as little as possible.
To give you an example, I once wanted to buy a second hand kayak, but the seller wanted far more than it was worth. When I asked why, he told me that he had bought it using money given to him in his Grandmother's will, and 'it would be disrespectful to her' to lower the price. The trouble was that whilst he was emotionally invested in the kayak, I was not, so chose to go elsewhere.
So to succeed at the game, you need to know how much your calf is really worth, and what the minimum is you'll sell him for (not necessarily the same thing). Then, if the maximum the seller will pay is higher than your minimum, you have the chance of a deal. If it isn't, then you don't, and there's no point in getting upset about it! There will always be chancers who want to get a bargain, but the place for them in livestock buying is the auction ring, not private sales, so don't feel you need to play that game if it makes you uncomfortable, or if you're unconvinced by the buyer.