A way to save on expenses is to have some meals, snacks and/or drinks in your room. If you are flying into Orlando and taking the Disney Magical Express to Walt Disney World, you don't have a car to go to the grocery store for the basic necessities. You could take a taxi to the store, but if you have the taxi wait for you, your savings could be eaten up. Even if they don't wait, the amount you pay for a taxi service could simply go towards a delivery service. Why take up your vacation time at Disney to go shopping when you could pay a delivery service to do it all for you?
There are a variety of different stores and delivery services that will deliver almost anything you want. There are stores where you are restricted to only buy what they have in their store and may or may not deliver beer or wine even though they sell it in their store.
Many families need specialty food. That's when you would want to hire a delivery service who will go to any store you want in order to bring you the items you need. Most of those services will also be able to deliver beer, wine and spirits.
As far as pricing, all of the delivery services charge a delivery fee. There are a large range of delivery fees. Almost all services lower their fee the more groceries you buy, but there is one service that has a range and charges more as the total goes higher along with fuel charges and "bag your own grocery" fees. Almost all will add money on the price of each item. Some have a minimum amount to order along with additional charges if you order alcohol. Be sure to review details of each company's fees before commiting to that particular service. Side note: most companies accept tips for the delivery service as well, which would be paid in advance when you pay for your groceries, because you, most likely, will not be at your resort to receive the grocery delivery.
Some of the Disney resorts have some items and will deliver to your room for a fee. This is the most expensive way of receiving groceries. You're paying Disney prices on basic groceries and they don't have a large variety. This is a great option for last minute or forgotten needs, but I would strongly recommend to walk to the gift shop and buy the item(s) directly and save yourself the delivery fee.
The grocery services deliver to your resort directly and can leave everything with Bell Services. When you get to your room on the first day, simply call Bell Services and ask them to bring your groceries to your room. Be sure to have a tip ready for Bell Services!
You could also ship non-perishable items to the resort before you arrive. If shipping items (UPS and FedEx) to your resort to be there upon your arrival, keep in mind they do NOT deliver on the weekends. Even if the arrival says Friday, be careful and consider package arrival a day or two earlier. People have shipped with an expected arrival of Friday, but the shipping company had a delay and it didn't arrive until Monday. Disney accepts packages up to 5 days prior to checkin date. Be sure to have the package sent to the person's name on the reservation. Remember that Disney now charges $5/package that is mailed to the resort. (Not including groceries delivered by a grocery company. Only items shipped/mailed.)
TIP: Some places offer a discount if you place your order well enough in advance.
UPDATE: As of November 3, 2018, I did a lot of research after trying to plan grocery delivery for my upcoming WDW vacation. I am sad to report that prices on delivered items have increased exponentially. Disney guests have reported that they have ordered the same exact items within 8 months and their bill increased $60 with the same company. I have found Amazon Prime Now to have the best prices. They have many organic items (Whole Foods) and not as many options of the same products to choose from, but I am STILL saving money by 50%. Let's put it this way, I reviewed an order of 12 items with one company, who I intended on going through, against Amazon where I added an additional 5 items and almost all of the other 12 items are now name brands versus generic. Ready for this? I cut my bill in half by adding more items and going with Amazon. I will be ordering my groceries on the day of arrival at WDW and all of it will arrive at my resort within 2 hours. Bell Services will take care of it for me from there, as usual, with all grocery services. And, there's no tip to pay, either, other than Bell Services. For those of you who don't have Amazon Prime or live outside the United States, because Amazon Prime may not be an option, I would suggest Instacart, who go through Publix Grocery Store.
Want some experienced input with what services are best to use? Go to our Facebook Groups and ask! Just click on these links: All Access Disney Group and All Access Disney DVC Members & Potential Members.