I'm currently wearing a pair of $400 boots which I love, so there's no way you'd get them for less than $600. If I was wearing flip flops, you could probably get them off me for $50. My point being that if you want to do this, your offer must be more than the shoe is worth both in replacement and emotional value.
I would not deal with you if I was alone because your proposal is too weird and I'd be wary of you.
In short, find a girl with cheap shoes who's in a group and you may have a chance.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.