Need a good online bandai japan toy link
If you are looking for the older Super Sentai mech ( anything pre- Gobusters), be ready to pay big bucks because the price of these goes up on the secondary market. For the older stuff, you can try:
You will have better luck finding what you are looking for if you look up the japanese name of the series on wikipedia and then using the japanese symbols for the series. You can also try buying the older Sentai stuff from a middleman service, who can bid on yahoo japan auctions on your behalf. Middlemen services do charge commissions, so be prepared to pay extra on top of what the auction+shipping will cost you.
For current Sentai stuff ( Gobusters and Akibaranger), keep your eyes glued to sites like HobbyLink Japan. When the preorders go up for the Super Sentai mechas, they sell out fairly quickly.