I have found the firms located in China and Taiwan and trading the goods interesting me. Some firms have statuses TrustPass, Gold Suppliers or both at once.

But I cannot understand to trust these firms or not? Because:
1. The given firms have no site on the Internet, and those that have very suspicious
2. Representatives of firm communicate with me by mail which is registered on free-of-charge post services such as yahoo.com, hotmail.com and others.
3. Methods of payment are offered 100 % T/T
4. To pay it is offered by means of systems Western Union and etc.
5. The pricelist of goods is made very carelessly and it seems hastily.

a) How do you think can i trust these firms or not?
b) Where i can check China or Taiwan companys by Internet?

Replying to [mrakus]: If you need to check some companies in Taiwan, I can help you..

Replying to [mrakus]:I think a company it must have "business licence" Maybe you can ask them to supply it to you.Or ask them to provide the testify which is via by the third institution.I think maybe it is better.
For the payment,you also can discuss with them.Maybe use L/C or you paid 30%deposit first.