Hey there.
Hi there. Are you still selling the bike?
Yes I am and it is a great trail bike. 
how old has it been used
It is about 6 months old.  I am just upgrading and won't need 2 bikes.  I have extra tubes and a pump to go with it.  
Are you willing to negotiate?
Yes, I can go as low as $120 cash if you can pick it up today.
wow that's great! I am so glad. Sure I can pick it up right today. Please text me your location and I shall be there! Thank you so much!
I sent you the address.  You will love the bike.
Thank you. So I shall see you very soon.