I live within walking distance of three large supermarkets where I do all my grocery shopping, but walking to a store and walking home with a load of groceries are two different things. I have a granny cart that I use now, but every time I take it out, I think there has to be a better way to do this (mine isn’t as fancy as those ones - mine lost its front wheels right away, and the handle is shorter and not covered). I see the strollers people are pushing around that are all ergonomic and with nice big wheels and all these bells and whistles - is there anything like that for shopping that anyone knows of?
Probably not the answer you were looking for, but a cool ideanonetheless.
I’d take a little red wagon over the granny cart or child stroller (or bike cart) anyday. But no, I don’t know where you can buy your own grocery cart. Have you inquired with the grocery store?
I found something called the Bag Buddy Cart, much like a stroller for groceries.
How about one of these? Would that work?
ETA: Dammit, criminey.jicket beat me to it! ::shakes fist:: 
How about this one from Stacks and Stacks?
I’ve always wanted to go into The Container Store and ask “how much for one of the shopping carts,” but I figure they’ve already been asked that a bunch of times. But you could go in, and when they pretend to laugh at hearing the same joke for the hundredth time, you could tell them you really mean it.
I’ve been thinking of getting an adult tricycle, some of which have just about as much carrying capacity as a store shopping cart. Unfortunately, they’re a bit expensive.
Regular shopping carts are easy to find. Just google “retail shopping carts.” That won’t help the OP, but it might help those of you with shopping cart envy.
I just bring a pair of guns to the grocery store
flexes
Our local flea market (Kobey’s) has medium duty carts much like a granny basket but larger and collapsible, and they sell for about 20 dollars.
I love that Bag Buddy thing! I’m buying one as soon as we move! We’re going to be within walking distance of a grocery store, but I figured I couldn’t walk for weekly trips because carrying all the crap back would be a hassle. It’s perfect! I can even take it on the bus with me when I go to farmers markets on the weekend!
(I used far too many exclamation points in this post!)
Perhaps this?
Check out Hubertand search for it. Im sure they have it there.
Radio Flyer makes several different models of wagon. I would use something like this rather than a shopping cart. You can get one with all-terrain tires and high wooden sides so you can fit more stuff.
I wouldn’t use a shopping cart because a) you look like a homeless person, and b) more importantly, the wheels get wonky in the damn store. I wouldn’t want to test one outside for very long. Oh, and c), if something breaks, it would probably be hard to find parts. 
After some Googling, the Sherpa Cart looks like it might be a possibility.
I’m not sure if you can get these in the US, but this style of cart/trolley is pretty ubiquitous here in Australia - I’ve got one to go to the shops or market, and it’s pretty stable and not too ‘I mugged an old lady to get this’.
Hmm. Some good ideas here, but I’m just not seeing what I’m thinking about. Maybe I should just get a used baby buggy and retro-fit it for groceries. As an added bonus, if anyone looks in to see my baby and just sees groceries, I can pretend that I lost the baby somewhere along the way, just for laughs. 
Don’t know of anything like that, but we have two of these that we use when going to the farmer’s market. I even bought them from there (the closest place to us in store is Vancouver…) and had great service.
Maybe you could invent one and make big bucks selling it?
My dad used to live very close to a grocery store, and he would just roll a cart home on a walking path (not rolling it down the streets) and then roll it back the next time he went to the shopping center. I know he was familiar with at least a cashier or two, so I imagine he had asked permission. It can’t hurt to ask, if you’re a regular at the store.