Why don`t you pick up the phone and start calling the manufacturers of products you would be interested in. They should be able to tell you exactly what they will and will not do. I believe most of them would want information from you, and want to know how and where you plan to sell their products.
I don`t know what type of handmade specialty items you are talking about, however as a manufacturer of handmade products I would wholesale to a person like you with a few considerations (ig. quantity per month, hand made takes time and I wouldn`t let you be too much of my business, minimum pricing, and shipping, would be a couple other considerations).
I`d say your hand made shops are probably pretty small and would be willing to have an outlet anywhere online or otherwise.
just my thought
As an independent sales rep of high-quality, all-natural, eco-friendly, philanthropic products (or as others call me, a `green` rep), I have to say that it`s going to vary from company to company.
The wonderful thing about green companies (which it sounds like you will focus on) is that they are trying to change the world, one small step at a time...therefore, the more exposure, the better....brick & mortar, internet, or bricks & clicks businesses (which sounds like what you will have). However, none of them would want to see their goods sold through ebay..even an ebay store. If you had your own website through which to sell these, this would usually be acceptable...or some might be open to amazon.com.
I do represent one company that does not want their products inundated on the web, so only a few websites (1-2 in each market type) will be privy to carry their products (and therefore, they will have a bit of exclusivity).
You should definitely be upfront with vendors as to where you will sell their products, as this will eliminate problems on down the line just in case they didn`t want the goods there. I agree that calling them to find out is a good idea.
A popular, classy website is a great customer for a vendor...in my opinion, it would be worse if you were taking the products to a flea market.. no one wants that.
The web is the present & the future. Most vendors realize that.
Other companies may differ, but the above is based on my experience from the 10 or so lines I represent.
I hope this helps.