I'd like to manage a few hundred virtual goods (cards, upgrades, etc), so it'd be really nice to be able to import all that data as JSON.  Is there a way to do that?

Got it.  I think I'll just use a few virtual goods then, and use collections to store the different types of cards.  I was thinking of storing each card as a virtual good, but I think that's gonna be a pain without being able to mass-import.  Thanks for the response!

if you really want that i created a basic http client on C#. I'll send you the method i am using to accomplish that.

        async Task<HttpResponseMessage> VirtualGoodRequest(string Destination, HttpContent Content)
        {
            await login();
            foreach (var item in temp)
            {
                client.DefaultRequestHeaders.Add(item.Key, item.Value);
            }
            client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));

            HttpResponseMessage messge = await client.PostAsync(Destination, Content);
            string description = string.Empty;
            if (messge.IsSuccessStatusCode)
            {
                string result = messge.Content.ReadAsStringAsync().Result;
                description = result;
            }
            return messge;
        } 

public async Task<HttpResponseMessage> AddVirtualGoodRequest(string shortCode, string name, string description, string currency1Cost = null, string currency2Cost = null, string currency3Cost = null,
            string currency4Cost = null, string currency5Cost = null, string currency6Cost = null, string iosAppstoreProductId = null, string googlePlayProductId = null,
            string wP8StoreProductId = null, string w8StoreProductId = null, string amazonStoreProductId = null, string maxQuantitiy = null, string tags = null, string id = null,
            string Tag = null, string propertySetShortCode = null, string segment = "[]")
        {
            var cont = new StringContent("{\"shortCode\":" + ((shortCode == null) ? "null" : "\"" + shortCode + "\"") + ",\"id\":null,\"name\":" + ((name == null) ? "null" : "\"" + name + "\"") + ",\"description\":"
                + ((description == null) ? "null" : "\"" + description + "\"") + ",\"currency1Cost\":" + ((currency1Cost == null) ? "null" : "\"" + currency1Cost + "\"") + ",\"currency2Cost\":"
                + ((currency2Cost == null) ? "null" : "\"" + currency2Cost + "\"") + ",\"currency3Cost\":" + ((currency3Cost == null) ? "null" : "\"" + currency3Cost + "\"") + ",\"currency4Cost\":"
                + ((currency4Cost == null) ? "null" : "\"" + currency4Cost + "\"") + ",\"currency5Cost\":" + ((currency5Cost == null) ? "null" : "\"" + currency5Cost + "\"") + ",\"currency6Cost\":"
                + ((currency6Cost == null) ? "null" : "\"" + currency6Cost + "\"") + ",\"iosAppStoreProductId\":" + ((iosAppstoreProductId == null) ? "null" : "\"" + iosAppstoreProductId + "\"")
                + ",\"googlePlayProductId\":" + ((googlePlayProductId == null) ? "null" : "\"" + googlePlayProductId + "\"") + ",\"wP8StoreProductId\":"
                + ((wP8StoreProductId == null) ? "null" : "\"" + wP8StoreProductId + "\"") + ",\"w8StoreProductId\":" + ((w8StoreProductId == null) ? "null" : "\"" + w8StoreProductId + "\"")
                + ",\"amazonStoreProductId\":" + ((amazonStoreProductId == null) ? "null" : "\"" + amazonStoreProductId + "\"")
                + ",\"maxQuantity\":" + ((maxQuantitiy == null) ? "null" : "\"" + maxQuantitiy + "\"") + ",\"tags\":" + ((Tag == null) ? "null" : "\"" + Tag + "\"") +
                ",\"type\":\"VGOOD\",\"propertySetShortCode\":" + ((propertySetShortCode == null) ? "null" : "\"" + propertySetShortCode + "\"")
                + ",\"segment\":\"" + segment + "\",\"_csrf\":\"" + token + "\"}");
            return await VirtualGoodRequest("https://portal.gamesparks.net/game/294321/virtualgood/", cont);
        }

   you use it like

AddVirtualGoodRequest("testff", "testff", "testdesc", googlePlayProductId: "com.google.testProject.testff");