That's about what I expected the price to be, maybe a little higher. I suppose the question that changes things for me is "would you pay more than $20 to buy a t-shirt?", and in some situations, the answer is yes. As an example, life is currently going good enough where I was planning on giving $150. Last time I checked, the closest tier was $100, but oh well. I briefly looked at the $250 tier (next one up), but nothing there really excited me, so I didn't think any more about it. But now, thinking 'would I go to $250 if it had a t-shirt', the answer is a possible yes.
Of course, typing it out, paying $100 for a t-shirt sounds ridiculous. But that's how people shop! If you look at the two situations separately, 'would I pay $$$ for a thing I really like' and 'would I pay $$$ for multiple things I sort of like', the answer to both could be no; but evaluated together, 'would I pay $$$ for a thing I really like and multiple things I sort of like, the answer may be yes.
All that being said, it still might not be worth it. The group of people like me who both are really excited by physical rewards, and have the money to pay the higher price could be pretty small. It would take someone with a head for business to figure out the number of people expected in tier w/o shirt, the number of people expected in tier w/ shirt, the profit form every person who moves from 'w/o' to 'w/', and the losses from everyone who were already going to donate to 'w/' even if it didn't come with a shirt, to figure out if it would be viable. My only thought is, in some situations it might be.
TL/DR: Never underestimate people's ability to rationalize throwing money away
PS: Is there a tutorial for posting? Once I was done typing my lengthy response the first time, I tried to quote Draco18s and ended up deleting everything I had written, which was more than I have now (maybe that's intentional to keep posts from getting too long
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