I research "wholesalers" "dropshippers" as a hobby. I used to research them trying to find one to work with on eBay. I signed up for the  Doba free trial about 6 months ago and cancelled. I just cancelled my second trial. Here's what I've found in a nutshell. Doba has not one single product at anything even close to wholesale. Their prices are at or above, mostly above, retail. You can actually go to most manufacturers own website and purchase the product retail at a cost approximately 20% less than Doba's "wholesale" cost. Then you must add Doba's membership fee, dropshipping fee, etc. As for being eBay "certified". This means absolutely nothing. All the products Doba offers can be found offered on Ebay at much less than Doba's "wholesale" price. If you research  an item from Doba on eBay you can see the sellers that are selling Doba products. Check their completed listings. They will rarely have a sale and when they do it's a sale to a brand new eBay buyer who more than likely did no price comparisons at all.
Another interesting point I've discovered in researching online companies with dubious reputations is that a very large number of them are based in Utah. I haven't discovered why yet. There are a large number of scams  and very high pressure misleading sales tactic type companies operating out of there.  There is a company right now that sells basically useless 500 mb websites for an obscene amount of money from Utah. They have been banned from Australia, Indonesia, and many other countries due to scamming elderly and fixed income people out of there life savings.
In conclusion. DO NOT sign up for a "membership" at DOBA. You will not make any money. If you have the cost of a DOBA membership and just have to give your money away, give it to your favorite charity organization. DOBA is not a scam as such but is definitely a company that makes wild claims, and is very misleading. They also have Many. Many, complaints with Consumer affairs, BBB and the like.
Don't believe me, Google doba, doba scams, doba complaints, doba reviews, and see for yourself.