Pulling data from different JSON files
There is no need using the 'this' keyword, or such as angularjs provides for those scenario. One thing you can do is to abstract the loadProducts functions and load prices function to a factory and then pass the factory as a parameter to your controller as shown below. 

var priceQuoteApp = angular.module('priceQuoteApp', [])
    .constant("loadProductUrl", "scripts/json/sample-products.json")
    .constant("loadPricesUrl", 'scripts/json/sample-product-prices.json');

priceQuoteApp.factory("ProductsFactory", function ($http, loadProductUrl, loadPricesUrl) {
        return {
            loadProducts: function () {
                //Create an object to hold your result
                var result = {};

                $http.get(loadProductUrl)  
                .then(function (allProducts) {
                    result.listOfProducts = allProducts.data.Connectivity;
                })
                    .finally(function () {
                        result.loadingProducts = false;
                        result.loadedProducts = true;
                    });
            },

            loadPrices: function () {
                $http.get(loadPricesUrl)
                    .then(function (res) {
                        result.selectedProductPrices = res.data.ProductVariants;
                      result.selectedProductAddOns = res.data.product_addons;
                    })
                    .finally(function () {
                        result.loadingPrices = false;
                        result.loadedPrices = true;
                    });
            }
        });


Then you inject the factory into your controller as shown below

priceQuoteApp.controller("quoteBuilderController", function ($scope, $http, $timeout, ProductsFactory) {
        var products = ProductsFactory.loadProducts();
        //Your other codes

        //When the user clicks the button
        $scope.clickAction = function () {
            var prices = ProductsFactory.loadPrices;
            //Then do other things with it.
        }
    });


One good thing is that this increases code return and thereby making every part of your code to focus on a single responsibility. Hope this helps.