I think I know the site you are talking about. Much more expensive than everywhere else and having it before anywhere else made me very suspicous of it.
I believe I also know this site, although I won't reveal it here obviously.
They wanted bank transfer rather than card payment for 6-APDB, which made me nervous, since you've no way to charge the transaction back in the event of non-delivery, unlike the well-established credit card payment chargeback procedure. However, the site looks genuine (it sells other, non-RC goods for which they WILL accept card) and also has a VAT number, which I looked up here:
http://ec.europa.eu/taxation_customs/vies/vieshome.do
...this site gives you the business owner's name and home address, which gave me confidence. I believe they only require bank transfer for this because Visa and Mastercard will not accept direct payments from merchants for chemicals. (Unless they use "Alertpay", who take a big cut, but are a bit cheeky and disguise the Merchant Category Code.)
My assessment is that this business is probably not a scam, but there's clearly risk.
Anyhow, I thought I'd take a punt on 1g of 6-apdb and paid by bank transfer. I received an email two days ago saying "DISPATCHED", but received nothing as yet.
If they don't deliver, I'll correspond to them including the name and home address of the owner and then file an online Money Claim (which is what people usually refer to, incorrectly, as the old "Small Claims Court"):
https://www.moneyclaim.gov.uk/web/mcol/welcome
It costs £25 but it's worth every penny. Also, you usually only need to threaten that you are
aware of the process (and how simple it is) to spur them into delivery or refund, since the result would be a Court Judgement filed against their business, affecting their credit rating and ability to acquire card transactions.
(I did this once before, for the record, and that's exactly what happened. I sent a (polite) email which included the business owner's name and address and details of how I was to claim, and got a prompt refund direct to my bank. Quite bloody satisfying actually!)
I'll keep you informed. Let's hope this isn't one for "LearnFromMyFail.com"...