You can convert your existing website to Marketplace using “Cybage” Marketplace plug-in. It’s Free and you can read Detail here… << Read >>.

After Installation, Product detail Page will Conflict with extension and Display unaligned Layout.
So, we have take care of View Page in Installation.

How to Install “Cybage Marketplace”. 

1. Install Theme First which you want to use in Magento Store.
2. Open View Page of theme.
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   (app/design/frontend/’your_theme_name‘/default/template/catalog/product/view.phtml )
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3. Ctrl+A (Select All view.phtml) and Ctrl+C (Copy All).
    
4. Now Install “Cybage Marketplace”. [Download]
    
5. Open View Page of Cybage Marketplace.
   —————————————————————————————————————(app/design/frontend/base/default/template/marketplace/catalog/product/view.phtml)
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6. Ctrl+A (Select All view.phtml) and Delete. and Ctrl+V (Paste).

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(Copy view.phtml From Theme and Paste in Marketplace view.phtml)
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