I get what your saying about limiting. The thing is, e-cigs are nowhere yet in Belgium. I am the first person that I know of to have actually tried it. And imo the future of vaping is not in working with liquids.
Different places, different markets I suppose. That's actually quite the opposite of what I see happening here in the US.
Must be some pretty confusing laws there, since you can really make a cartomizer with any concentration of nicotine you choose. I would think that one possible venue might be a niche within the niche and sell custom filled carto's? That of course would depend on the licensing requirements and how hard/expensive it is to get licensed to do that.
It just seems that reselling what is already available is reinventing the wheel a bit - since I got from your post that you were looking for an internet based business as opposed to a storefront. I know shipping from from China or the US would be a pain, but there are a number of UK based suppliers out there.
So would being an internet only enterprise help with the legal issues? It really sounds like you have a rare ground-floor opportunity there. Could be awesome if you find an efficient way to get through the government red-tape.