unless your shoe size is like 15 you don't need 30.5 boots. sure the system claims thats the correct size but you won't get what you need out of the boat.
I have a pair in 29/29.5 that I will likely be looking to get rid of soon, and they have already packed out. (this would be the reason for the sale) However, until you go to a boot fitter I will refuse to sell them to you.