I always source my stuff from few places, lemme share em with you guys:
Amazon.co.jp + Tenso is a good place to get cheap stuff. Amazon always have discounts, and Tenso (package forwarding service) is quite reasonably priced. Only thing is you need to guesstimate some form entry pages since some are not translated in English.
Or can try yokattaweb.jp also, have good experience with them. Very very fast service, order on Sunday, get items by Friday. They will hunt the item for you and send it to you, only drawback is pricey compared to Amazon + Tenso.
For those looking for HMO Miku, XL-shop has stock, probably won't last long. I got mine from TFM (thefiguremall.com). Good service, been a regular for more than a year now.
As for PO cancellings, it's not a surprise, I guess they already wanted to cancel all the POs ever since got JP investor wanting to buy over the business, so now would be a good time to legit cancel all the POs. (Just speculation)
May I know how much is the shipping fee for a typical nendoroid if i used the tenso service?