Great poll idea. I would like to buy and sell directly on steemit too, but am holding off due to a lack of user control over content. Steemit.com's disabling of edit and delete functions really kills the ability to maintain any kind of storefront here. If you cannot manage your posts like sale ads, sold items, keeping content\prices correct, and deleting sold\unavailable items, then you cannot really project a professional image.
Another poll that might be interesting is "what features are holding you back from selling on steemit".