They will ban you, If you cancel a listing then list it up the next day, A couple of times, They begin to see a pattern in you're account, Don't you think everyone would be doing it if you could do it all the time, People join ebay for bargains ''cheapest price'' if you're going to cancel when you don't get the price you want that doesn't really belong in ebay,

You would get away with it a few times but people will start complaing, As i know i would if someone did that too me.