If you're on Facebook, there are several legit coral auction groups that you can join. Search and simply request to join the group. There's even a group that lists vendors to stay away from. Vendors and hobbyists alike put their inventory up for auction quite often and you can definitely score some really good deals, if you are quick enough to bid high. PM me and I can point you in the general direction, depending on what you are looking for.
As far as payment, PayPal is king. Payment via PayPal using credit cards, if you can, so you can file a charge back with your credit company in the event something goes wrong in the deal (don't abuse that privilege). NEVER send payment as "Friends and Family" through PayPal, UNLESS you really are a friend of the vendor or you've done enough business with them to fully trust them (even then, most reputable vendors will never ask to send payment via F&F). This way, you're covered somewhat via PayPal's buyer protection agreement, if you do not receive the product you paid for.