Hello! Fellow american who is looking for the g3 giants. You should poke around facebook groups and facebook market place for them. Australia/new zealand have their own mlp buy sell group. Its closed but if you just say you are joining from the us so that you can get a better chance to find the g3 giants they will let you in no problem. There a decent number of active mlp buy/sell groups on facebook so id recommend joining a few. I got my giant minty through facebook
I personally have a daily routine where i search ebay for listings. Ive gotten my frilly frocks and my sweetberry through ebay (US ebay!) Listings. I sea4ch 'my little pony plush' and make sure i set categories to all and item location to worldwide. Then sort by newest listing. Listings for the giants will come up every now and then so just keep checking and youll find one.
Frilly frocks in particular WAS released in the US so you might be able to listing for her on ebay/facebook currently. I know there are few listed on Facebook near DC, although they are very over prices currently :/ you could probably barter them down