I understand the other issues it may cause, but I think 'calculate' is a bad feature as well. eBid should track your location and details and work out the prices before you click onto the auction. Without P&P Lowest First as a buyer I was terribly confused. I was trying to get a close friend to sign up the other day and he was checking it out and asked me to search for an item and he also complained about P&P lowest first not being included, without me even saying anything.
I'm going to persist with this idea because I really enjoy eBid as a whole.