A high goal on Kickstarter /is like a high price/ and seems to trigger similar supporter/customer behavior.
When I saw the Light Table video on HN I flipped out. I want this! But when I saw this campaign something cooled my jets. I'm not sure I'd pay $50 if it was for sale right now. If I'm supporting its creation, and speculating at that, I need a more alluring price and/or a story that makes me forget about all price concerns.
If I were the creator, I'd seriously consider pay-what-you-want.
In this case, it's not a matter of presumption, it's a matter of knowing the reality of what is involved in actually building this thing.
Edit: I did't mean to suggest the goal is unreasonable or unattainable. I was just trying to explain the not-positive reaction I had to seeing it. Like shopping, not all price reactions are logical.