build a short conversation of asking quatity

A: hi
B:hi
A:what are you doing?
B:i'm searching the good shoe to run
A:why you not ask to the seller?
B:good idea.

A:excusme sir.. do you know the best shoe to run.
C:sure just try nike..
B:are that the best quality in this store?
C:that is the best quality i know
B:well thanks sir,i chose nike.
C:that a good chose.