Look at the Big Max bags. Not a big player on the market yet but they are great for the price. I have the hybrid bag and it easy to care and waterproof. All for $179. Their push carts are an even better value.
If she is a good friend of your wife then I would ask your wife to inform her how out of line she was by cooking in your kitchen and lecturing your children.
I would go to dinner at their house next time and cook my own food once they are done. But I'm petty when someone comes to my home and acts like an A hole.