There were a couple of issues I fixed.'
1) The paths to the confirm and confirm_cart pages referenced on the checkout page were wrong. They included a ../ when they are in the same directory.
2) The form code was too high on the page. The wizard can do that sometimes. I copied and pasted it back into place.
3) Your blank per-item tax field caused errors, so I removed it. It shouldn't be there when it is blank.
4) Your complex pricing was causing issues with checkout. Since the price * quantity didn't actually equal the total price since you charge the extra $1000 base fee, I solved that by passing the entire row as quantity = 1 with the total price to paypal.