An annual membership to Doba starts at $600. They claim 33%-75% profit margins on their inventory, which while I personally consider that an absolutely nonsensical claim, for purposes of illustration I'll say "assume a 33% profit margin."
At 33% you need to be prepared to sell $6,000 a year in volume to clear a net $100 and change after eBay fees, payment processing, the Doba membership fee, and taxes.
-$ 720 eBay fees, payment processing and related expenses
-$ 600 Doba membership
-$4,500 cost of product
$ 180 before taxes
Obviously, you might be able to find some stuff with higher margins, get your operating costs down, etc. However, no matter how you slice it, the profit margins at best aren't going to go too much over normal dropshipping margins, which tend to be less than 33% rather than more. And you could also spend more -- significantly more -- on your Doba membership, depending on options and how you pay for it, and that large of a number all but dictates that you sell well into four figures or even low five figures a year worth of Doba merchandise before you get to make any money that you keep.
Not a dig at Doba in particular; just an observation that the math in this business is brutal enough without having to move the goalposts even farther back to cover high-dollar memberships of any type.
Doba was featured Link hidden: Login to view a while back; some other info there.