Buyee stores your items for free for 30 days and allows consolidation. You can for example purchase on Amazon Japan those items which don't ship to SA and you can consolidate them in one parcel. Of note one should be careful about big and light items as DHL sometimes doesn't like large items but there is a shipping calculator you can use, so a small and heavy item may be cheaper to ship than a large number of big but lighter ones: volumetric weight.
At shipping, on Buyee at least you can edit the customs declaration, so if they misclassified something, you can change the tariff code yourself. Of course they will refuse to lower the amounts artficially.
So they function much better. Coupons also exist. For example using a Buyee coupon I purchased a product on Rakuten Shopping which actually cost me less than it would have otherwise including their fees, and fee discount coupons are released often so you often don't pay the fee or the local shipping because discounts. Zenmarket also stores for free for up to 60 days. Discovery Japan I've only used once for a single product.
You pay the shopping service and they can also buy the item for you, or you use their interface for Rakuten, YJ and Mercari. I suspect Buyee make their money by claiming back the VAT. They don't deduct the VAT although Discovery J did deduct the Japan vat on an item for me, as it's meant for export. But with AGS you also can't claim VAT back as it's a local sale.
For single items AGS works well, with Amazon at least. But for consolidation you're a bit st-ffed.
AGS also has a problem. I wanted to buy something from Amazon Singapore but that site requires an SMS code be sent to verify delivery. AGS apparently can't do that.
I ended up buying a similar product for less from a Japanese website.
