I do that all the time. Just bring a certain amount and put the necessary items up front and then if it is too much (more than I anticipated) i ask her to take the remaining groceries back.
Whilst i find in this current economic climate one must be price conscious, so I do find that I am more loyal to my purse than I am to the "soul traders", whose prices can be exorborant. Nevertheless, I will only buy my meat, fish, and poultry from one specific craft butchers. I am loyal to my meat lol.
All over europe a recent addition of more generic brand shopping stores have been added. These are called Lidl and Aldi - just generic core brands, not the augmented variations of such consumer brands. The box of stuff is cheaper than the plastic smaller container. perhaps 2 euro different in price and the same core product in the box - their tricking device lol. It took a long time for people to embrace these methods. What was perceived by the customer of mass produced products for the mass market wasn't tha actual reality. Soon the snobbery went out the window when they realised that for same basket of goods, they could make a saving of 50% rather than spend their money in the more long established super-market chains. People of all walks of life now shop in these standardised stores to save the extra buck so to speak. Nevertheless, the shopping with "no trills no frills" has come with somewhat of a disadvantage to some, if one does not drive, which is common in the United Kingdom. I am lucky as there are two of these stores in town. Nevertheless, I think the concept is excellent in terms of managing a change in consumer behaviour. These stores on a weekly basis introduce new limited products to attract retained and potential customers. I personally think their fruit and vegetable selection is great - much better than the giant supermarkets.