Does anyone have a Costco card? Are they a viable alternative to high street supermarkets for regular shopping?
Yes. No, sort off.
They stock some things all the time (from cornflakes to ketchup to butter to fruit and veg) but other things are luck of the draw.
I've been a member for many years and use them every month to six weeks (now I am down to one freezer) and mostly buy chicken, beef, lamb, salmon fish, cereals, cooked chicken breast, mince, Lurpak and the like. The quality is decent and a lot cheaper than the supermarket especially those items (twin 1kg cornflakes less than one box from supermarket). Oh, and loo, kitchen rolls, tissues, cleaning products, washing powder/tablets and dishwasher stuff.
The main reason we don't buy fruit or veg normally is that they are always sold in large quantities….a tray of twenty oranges, a whole banana tree, enough lettuce to keep a petting zoo going
As others have said, their customer service is great and warranties excellent. If you are considering membership, Trade is better because it allows entry at 10am before everyone else at noon and if you can get a little group together, Executive Membership is good for the money back side. I haven't paid for membership for years using this scheme.