seems you are just arguingif you know a bit of today's market, how can a seller have a good position?
if you are just talking about theories, your message is also wrong.
GST is legal requirement, unless your want to be illegal, GST MUST be paid.
The portion you can bargain is agent's commission, but no matter how much is the commission,you still have to pay GST!
ask agent , 1% * 93% is his commission
and buyer still pay gst 1%*93%*7%