To give added credit where due, I don't know if it was in here or elsewhere, but Rick had mentioned the idea about seeing how many people wanted an item and what star ranking they gave it. It's a good idea and would be fun to see. I was glad he brought the idea up.
...however, after consideration, I realized that it might take some of the fun (and maybe even some of the strategy) out of the game. If people can just add more seeds in later in the game, my concern is that two things could happen:
1) the fun of 'dibbing' an item would be compromised because if there is enough for everyone of that particular seed, there isn't much feeling of victory in getting it. As I understand it, this was a large part of why my initial idea of how the swap setup should go was discarded in the beginning stages of the seed swap movement here on the site...it was more fun to simply go 'all in' with your seeds and offer what you have....and that quantities would be somewhat limited so that people were motivated to make choices about what to bid on first and get excited about being able to 'win' it.
2) if the additions are added later (i.e. on the third day of the swap, someone adds more packets of calendula, for example), the people who thought it was a scarce item and used one of their early bid tickets on that item might feel cheated in a way since they could have used those tickets on items that were truly scarce.