> are you

> - agreeing there must be some threshold such that if the price is $X then you will buy(/bid on) the item, but if the price is $X + $0.01 then you won't;

No, I'm not. If I will buy an item for price $X, I will buy the item for the price $X + $.01. The decision to purchase something is more complex and cannot be encapsulated as one single dollar value.

I think something your model fails to account for is: there is friction associated with a purchase. I will not necessarily go through the process of buying something whose "value" is $0.1 even if its price is $0.09, because there is friction to making a purchase which that $0.01 profit doesn't cover.

As an example: I recently played a Pokemon ROM hack where there was an NPC selling a nugget for 4999. You can sell the nugget for 5000. That's 1 coin profit; objectively a good trade, right? But going through the process of purchasing something isn't free. So in spite of what your economic models may suggest, I did not stop everything I was doing and spend the rest of the game buying nuggets for 4999 and selling them for 5000, because that would've been boring and my time has value.

If I've already gone through a lot of the process to decide to buy something at a certain price (which includes doing research to find out that the thing suits my needs, researching how the market looks for that category of thing, then bringing the item to the cashier or engaging in the eBay auction or contacting a seller), then I've already spent some not-insignificant amount of resources on the purchasing process. A $0.01 price increase will never be enough to stop me from completing that purchase, because $0.01 is not worth going through the whole process again.

If I'm already at the point where I want to bid on an item at $X, then I have spent more than $0.01 in effort researching things to bid on, so I would also bid $X + $0.01.

eBay explicitly bans AI "buy for me" agents in user agreement update