The value of 1/1 cards?

[Dalkowski110]

"Do we the collectors decide based on demand?"

You nailed it. I scored the 1/1 Pedro Martinez from the same set, btw, 2008 Topps Moments & Milestones. Generally, depending on the player, they could go for anywhere from $5-$100 and values DO fluctuate wildly.

[howiek]

I asked a question on the pack pull thread and figured it was the wrong place to continue. So, here it is. The Yankee dude said that the 1/1 cards are not listed on Beckett. because they are rare. So, How and who determines the value of the card? Do we the collectors decide based on demand?