Continue finish half-built online marketplace

I had a developer who had to stop just after completing what seemed to be a bit more than half of the website, which I believe uses PHP Codeigniter and MySQL, and have been unable to find a new developer so I am using this freelancing website for security (my current developer has been paid 3 weeks ago and has not shown me any work or been in good contact since); hopefully this goes well. It is an online 3D model Marketplace, where you can buy, sell/display, and request the rights to 3D models, and find 3D printers near you to eventually print it. Here are the remaining features; more details will be provided upon hire: - A payment system (connection to Paypal and a few credit card API's) - Connection to MakeXYZ/Shapeways and to get the locations of 3D printers near the user - Model request feature/section (you could probably reuse the code that's already made in the gallery/marketplace for this) - Implement JS3D - Fix any theme or backend incompletions or bugs such as missing / poorly placed icons, small items missing like profile fields (like implementing payment information account fields while you're doing the payment system) - Help get the files and database and Amazon AWS set up onto our server after testing and all it is a functioning 3d model marketplace site The payment was originally $500, half of which ($250) went to the first developer, but I understanding that it may be a pain working through his code so I am upping my valuation to $600 such that whoever completes the site will receive $300. To clarify, the budget that has been allocated for completing this is now $300.