The Goodings (that's the name of the store) at Crossroads is a tourist trap.
it has a limited inventory, mostly geared towards tourists, and beware of the sticker shock ... I've found some items to be less expensive at the hotel's little store than at this *supermarket*
if you're going for basics, you might as well go to the speedway service station that's just opposite the marketplace at Disney Springs (or as Beth advised, the one across from the Boardwalk, same service station chain)
I wouldn't walk to Crossroads from Disney Springs. The heat would be too unbearable for us, even though it's only 25/30 minutes from DS, it's still too much on top of the walking in parks.
If you want a more efficient and satisfying shopping run take a Uber to the walmart on vine street in kissimme. that's around $15 each way with UberX. That won't be cheaper than walking to Crossroads, but you'd have a larger selection, especially if you need specific items. Don't try to use the Lynx (bus) you'd be in for up to 3hrs round trip.
The DVC advice is good, they usually have a wider selection, and even if the prices are higher than at the stores, the time saved, as well as not paying for transportation will offset that cost overhead.
Your other option is to have food delivered to your hotel.
You can use Garden Grocers ($40 minimum order, $14 delivery fee, 10% off if ordered more than 60 days in advance)
but you now can have items delivered FOC, in 2 hours by using
Amazon Prime Now
you might be able to sign up for a free prime trial on the US amazon (if you're not already a customer of their US prime) in which case don't forget to cancel after use.
When you're a member, you can order online and be delivered in 2 hours without fee, direct at your hotel (you can even order from the airport or on the way to the resort on the magical express if you have data in the US
)
Disney might put a $5 delivery fee on every box shipped to a hotel (convention center or regular) but it seems that Gargen Grocers and Prime Now are exempt from the fee, for the time being.
As far as declaring the food. Many people don't declare, and get away with it.
But, if you get caught, and even if the food is admissible, if you failed to declare, you're in for a good lecture and a not so very nice talk-down from an officer. Not the best way to start the vacations after a long flight with cranky kids and fed up parents.
So, declare, it's free ...