The Foodland Farms Grocery store was cheaper than going to Kona! Mauna Loa Macadamia nuts were on sale cheaper than WalMart! Beer is very reasonable also. I've found this grocery store to be a convenient, inexpensive alternative to the hotel food prices when I want snacks, breakfast or lunch on my own.
There was also free entertainment both times I came to the Mauna Lani shops. There isn't a huge variety of shops, but you'll find the necessities of a resort stay here at reasonable prices, and maybe some souvenirs too!