Seeking a multi-store e-commerce platform with distributed transaction processing and shared user base

Does anyone out there know of any combination social media/portal platforms with a multi-vendor shopping cart that supports individual vendors clearing their own transactions?

Let me explain in more detail:

I am in the process of selecting a platform for a combinat开发者_StackOverflowion e-commerce mall/social networking site. So far I have had little luck identifying an appropriate platform. The general business concept is to provide a website that brings together a particular buying demographic and crafters and other small-time production operations whose wares are of interest to that demographic. The site is to provide a lot of social media/value added content of interest to both the buyers and sellers as well as the ability of sellers to set up shops and sell their stuff to buyers. Existing sites that are roughly similar to the envisioned one are etsy.com and artfire.com.

There are lots of social media/CMS platforms out there. The crux of our search is for an appropriate e-commerce platform that will integrate well with them that supports the following requirements.

• Vendor participation in the site will be on a tiered subscription basis.
• Each vendor will establish their own "store front," enter their own product listings, clear their own transactions (primary through paypal accounts), handle returns, etc.
• Store front layouts will basically be the same, with options to customize color scheme, graphics and most textual content.
• There will be a common user base across all shops and social content. A buyer can buy from multiple shops w/o having to sign in to nor have an separate account with each.
• There will be a common taxonomy and search ability across all shops/products.
• Product search needs to be separate from general site content search.

One important aspect is that most of the vendors will be part time sellers and by no means tech-savvy. Thus we need to have a very simple and easy to use store management UI for them.

Our ideal platform would be open source (or source code available) with commercial support available and preferably built on the .net platform.

That is the wish list. Our research has not turned up anything especially appropriate. So I am throwing this out there to see if anyone is familair with any platforms that may be suitable. If its open source, we can tolerate needing to make modest modifications (particularly developing a simplified UI for seller) but trying to morph a single-store platform into a multi-store one, or morp a multi-store site that expects all transactions to be cleared through the site owner is beyond what we want to tackle.

There is a classic buy vs build issue here. No available frameworks means there is insufficient common ground between those kind of applications (or not enough money to be made, but that seems unlikely). They might look the same, but might have very different performance drivers.

Considering the scalability issues you'll have to tackle, it's likely there is not much open source platform available, especially not well-tested. The problem is that when you go multi-vendor you increase the complexity. You're unlikely to have the same scalability dimensions as the original users and developers of those platforms. I'd guess most similar platforms are custom made, reusing lower-level libraries. You might have better chances in the RoR world.

In the Ruby on Rails world people are much more likely to create an open source framework, when compared to the .net world. There are a lot of libraries. That is the main advantage over Smalltalk/Seaside, which I would recommend for its productivity in building custom software (about a factor 5-10 faster development than .net for custom development, when compared to my earlier employer). There's one environment that would allow you to combine both, that's MagLev.

The only thing I've seen remotely close to this is Ubercart on the Drupal platform. Ubercart (and Drupal) are "Content Management Frameworks", in that everything is modular and can easily be extended. Most shopping carts are built strictly for one merchant, one payment account.

There's an Ubercart Marketplace module at http://drupal.org/project/ubercart_marketplace that implements what you are talking about, but it works by accepting payments into your account, then merchants are cashed out using Paypal Mass Pay. Still, it may be a good place to start your own custom development.

For this custom development, you'd want to intercept Ubercart's submission of a transaction to Paypal and replace the store's Paypal address with the Merchant's address so payment is processed via that merchant's account. The merchant's Paypal address could be a Profile e-mail field.

We have found one product that appears to do what we want, PHP Mall. We are testing it out now.

I would suggest you to try Bitcart (http://www.bit-cart.com). It offers marketplace software with distributive payment systems for marketplace sellers as per your requirement.