Shopping at the Street Market

I had to buy some apples for District Primary Training tomorrow.  Here's a picture of me trying to figure out how much 24 apples cost.  I also bought 2 avocados from the lady next to the apples.  I can say "con bien?", (how much?), but when they answer, I can never track what they say.  So, I hold up a few bills and let them pick.  Some have taken advantage of me, but most are fair.  If I think they are being fair, I will give them back a little "tip".  I remember where I have gone before and try to go back to them.  It isn't always easy.  There are shops for bananas, avocados  pineapples, watermelons, tomatoes and apples, but they are usually not together.  I'm getting better every day.