Where can I find information about an online store?

I am looking to buy a new cellphone and have been looking all over the Internet. I have come across some sites that the price looks too good to be true, which in most cases as you know, is. Then again, some sites have prices which are lower than what I have been seeing, but still in the back of my mind I think well I have never heard of this company, are they just going to rip me off? Is there a site where I can type in the website, company name, etc., and find out if they are legit or not or if there are reviews of them? I know not all of these sites can be scams. TIA.

1. www.epinions.com

2. www.ripoffreport.com

3. enter the name of the company and the word 'complaint' into google.