They all look alike

So I just went outside to buy some food to eat and some bananas.
There are always people with bicycle carts of fruit, so I stopped to
look at some bananas. These first two ladies had some, but I knew
from experience to look for gashes in the skin and soft spots, so I
inspected her bananas. I ripped off two that I didn't want and she
started to weigh them and said 1 kuai for one banana. So I said one
moment and walked to the next guy. He also had a bunch with some soft
spots and gashes, he said 1 for 1. So I walked to the next guy who
proudly showed me his bunch. They were all very clean and intact. The
ladies had been laughing this whole time, I guessed because I was
being smart and inspecting the selection, but who knows. The guy with
the clean bunch said 2 kuai for one, obviously because I recognized
his bunch was the best. So I said too expensive and walked back to
the ladies. I said si ge si kuai, meaning 4 for 4 kuai. I handed her
a 20 bill and took my change and was sort of talking to the other
vendors, who were laughing. As I walked away some little girl who I
often see selling flowers who is really annoying was walking with me,
asking me where I was going. I told her to the store. I felt in my
pocket and realized I only had 10 kuai, not 16 like I expected. Then
I realized the lady gave me only 10 back, she probably cleverly said
shi instead of si, meaning, "ok I'll give you 4 bananas for 10 kuai
(you stupid white boy, thinking you can comparison shop me)". So I
walked back, and the guys were there chatting, but the ladies had
disappeared. I asked where they went and the guys said they left. So
I walked a ways and saw some ladies with carts and went up to them.
They acknowledged me looking at them, but thats because I was looking
at their carts to try to recognize them. The ladies did not look
entirely familiar, but they all look alike and I think there is a
regular crowd of vendors that I normally see. I tried to say some
words but didn't know what to say. They started riding their bikes
back to the original place and I gave up. I went back and talked to
the guy with the clean bananas, and he told me "you should have
bought mine, I would have given them to you cheaper". So I left, I
was talking to some girl I knew telling her about it, and one of the
regular beggars came up and pointed to my bananas, he wanted one. I
managed to explain to him my story and he laughed and said it was ok
and left. It must be a game around here, who can trick the "lao
wai"?, literally old foreigner, but used for foreigner.
I'm just mad at myself that I didn't check my change and that I did
not have a better memory of the ladies' appearance.
Now I need to learn some cuss words so that when I go fruit shopping
again and see them I can let them know I mean business. If they know
you mean business, they are great to do business with.