I got my 2019 Si for $22,997. Sticker was over 25. There are deals to be had.I don't think $23.5 is a terrible price for a "used" Si with 400 miles on it. I've looked at a lot of used 2017 Si's and they usually are at least 22K with 20-40K miles on them. There's simply no deals on these cars out there, it's amazing a two year old Si keeps almost all of it's value.
But, with it already having a dented bumper I don't blame you for giving up on it.