"The bad thing about the internet shops is that the odds are you will get hosed sooner or later" <--- It's not a given but it is a possibility, which is why I do my due diligence first before clicking the checkout button. Ebay can really be a crap shoot if you don't keep your eyes open. Lot's of sneaky bastages on there, but then there are many many more sellers that are great. I have been buying and selling on ebay for years and I rarely get porked, but I can see how a noob who hasn't done his research can get easily hosed. The good news is that Ebay is so .... attentive toward it's buyers that if you do get porked by an unsavory seller Ebay will normally make sure you get a refund.
As far as online vape shops or vendors go, I never just google a product and buy it from the first couple of sites that pop up, nor do I always buy from the vendor with the lowest price. I check ECF and google for any red flags raised about the online vendor and look for reviews about them. I look for the most trusted dealer with the lowest price, including the shipping cost/time, who carries exactly the model # and version # of the item I want and offers a warranty. It can take some time to do the research but for me that's part of the process and I actually enjoy it. Not to sound like too much of a dork but it's like the thrill of the hunt for me. It's almost a letdown to finally pull the trigger on something but I do love checking the PO box for new vapemail.