Part of being a dealer is being able to correctly value a coin given current market conditions. Simply saying a coin is worth what someone will pay for it is a cop out. As for your Morgan Dollar, I'm having a hard time following your story. Did you buy it raw and have it graded? PCGS doesn't value coins then look up the corresponding grade, and to suggest such is just silly. I know you didn't ask, but if you handed me that coin and asked me to appraise it, this would be my answer. The toning while attractive doesn't present in a rainbow progression as a bag toned Morgan Dollar would. In that respect, you will lose some of the potential buyers looking for a rainbow toned coin. That said, the coin is fully enveloped on the obverse and the blue patina is very attractive. The crescent of russet toning on the left may turn off some collectors but the coin should still garner a decent premium and sell in the $175-$225 range.
And I am not a dealer. I did not imply that I am one. I have met many dealers whom I will simply listen to because it is very apparent that their knowledge of coins is far superior to mine in every aspect. I have also met several (thankfully far fewer) who are so unaware of what they have that I could dance circles around them. And the rest are the ones where we share knowledge and help each other out. But a basic Economics 101 fact is that market conditions are set by how much people are willing to pay for a good (or service). Yes. I know they don't. But, as you said, they assign a value to a coin by giving the grade they felt the coin was worthy of having. And market grading is a perfect example deciding its value and then assigning its grade (or more-accurately, bumping a grade up or down to reflect their opinion of value), a practice you accept and back up. Thank you.
Its just because I'm on my cousins lap top. Once I got on my computer I realized that it was a 67 and I'm not a rookie