There is a blue link beside Choose Format and Price -> Add or Remove Options.
You do know that your opening is a Reserve, right? In that, no one can bid lower.
Many people will pass on an auction with a hidden Reserve, not wanting to waste a week and still be lower than the hidden Reserve.
In addition, whether the Reserve is met or not, your fee for the option is not refundable.
OTOH, looks like we have a 500 Free Auction Listings promotion.