If you want the best price, always buy from a Japanese site like HLJ or AE. Be aware that they put up their listing way later than other retailers and often don't have enough supply for demand. For example the Legends Fembots, TAV Insecticons and TAV Minibots all have been hard to source from Japanese retailers recently.

I've never used TFI or PC, but they seem like good Aussie sources. I do however prefer to buy from stores that don't require payment upfront cause something could always go wrong.