I am very interested in this project. I have worked a bit with CSV files in the past. CSV files are one type of file that can be dealt with in Excel, although other formats such as XLSX can be used if you wish. I would prefer to do this project in C#, but I also have some experience with Java, C++, and Python. As for a timeframe for the phases, the first phase will take the longest and the following phases would basically just be using different templates. For the first phase, I wouldn't think that more than a day or so would be necessary, depending on how nice you want the interface to look. The interface can be either command line or an actual interface. I do believe an actual interface would be more helpful to this application, but the choice is up to you. I use Newegg and Amazon quite a bit and have used eBay a lot in the past. I have never used the website for Sears but it seems to be like any other online marketplace. As for documentation, I will provide both instructions for the end user and in-code documentation for anyone that wishes to modify the code. I hope to be able to work with you, please let me know if you have any questions!