if he is in the process of nego-ing, then only he cancel the deal i think still ok and acceptable.

coz they havent agree upon anything right?
correct me if i am wrong on this.

if every time we saw something tat we like to buy, its not wrong to ask and enquiry about that thing so we dun buy the wrong stuff and get into any argument, but if by nego-ing and asking like this buyer expect ppl to 100% get their item although we can find a better deal elsewhere is not right.

if like this i can put alot of ppl in MO list and also kena put in MO list by alot of ppl.

unless imperial adi confirm tat he is goona get that item and arrange for cod or agree to deal else i dun see any reason why he cant back off

because

1. found a better deal
2. seller slow in replying ( we dun even know if the item is still available )