The only thing "wrong" is that you are a new seller of a relatively expensive item that will attract lowlifes,
Change to Fixed Price, Immediate Payment Required, PayPal account required.
The one thing your non-payers have established is that your price of $450 is as much as you are likely to get.

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915
- answering Trolls is voluntary, my policy is not to participate.