Hello
Hi
Are you interested in purchasing the bike? It's in great condition. 
Yes! How does 115 sound?
That's a bit lower than what I am offering. I'm not sure I'm willing to go as low as your offer. Considering the condition, recent tune-up and upgraded parts, I don't think I can go lower than $150. 
Considering it's condition, and your knowledge of the bike's accessories, I'd be willing to pay that much.