I cannot offer any specific help or make a reccomendation here but my own technique when trying to evaluate a potential web based supplier works like this.
1). Check the site. Is it a big site? The bigger the site, the more trade it usually has done. If it is a less than 10 page site that some kid could have cooked up in his bedroom, move along.
2) Look for negative comments about the company on Google. Type things like "ABC Company, crap" or "bad" or "rip-off", "ripped". Stuff like that. If you find none, it's good news. Find a load, next site please.
3). Look on the site for feedback. If the same 3 people have put in the same comments or the comments are very, very similar, then the feedback has been faked.
4). Do that take PayPal? If they do, then the company has been vetted by PayPal and they should be OK. I know that opinions on PayPal vary but I find them to be a good yardstick.