What you have to remember is that there are tons of forums out there. This site isnt the end all be all of rc classifieds. Just because they are new here doesnt mean they are a bad buyer, it could mean they just found the site.
If you are worried about it, ask if they have feedback in other forums, ask if they have ebay feedback. You can also search their paypal email and see how long they have had it, and if its verified.