Insertion fees cap at something around $4-5 no matter how high your starting bid IIRC.
Of course if someone bids on it as a joke his eBay FVF fee will be astronomical. I don't know how eBay handles that sort of thing. (i.e. if they streamline the FVF credit process or if the guy really has to pay the full fee and then just gets it credited back as an eBay credit. Ouch.)