I think that each platform really needs to handle the tax part of the business model for their third party vendors – there is no way that a small seller can handle this for each sale they make. Also, these venues like Amazon and Ebay are very clear with sellers that the customers are NOT OURS – the customers are theirs… we are not allowed to interact with them, we are not allowed to up sell etc. So Amazon should collect the sales taxes from every sale on there site imo.