Yes, if you buy 1000 CET with BCH you pay 0,1%fee so you get 999CET. So you have to sell those 999CET and pay another 0,1%fee and end up with the same amount of BCH you began with.
Better to just buy it then, the trading is discounted, but not free - unless there is something about bots to compensate that I do not know off.
