personal inventory web application

I would like to have a website application created however, I have no idea how much time and skill it takes to create such a site and therefore I am coming to you to help me out with it. It is for this reason that I indicated this as a low budget project. I have a vision of what I want, however, the details are all still to be worked out. I am looking to have created; a web based application so that users will be able to create personalized inventories from lists of items from the application’s database populated by me. An additional payment and on line account feature on the website will be similar to a classified / auction type of application. The user will be able to indicate whether the user has such an item in their personal inventory. Additionally, the user will be able to indicate certain aspects of his particular item such as condition, make, model, color, include notes regarding that item, upload images, and also indicate whether the item in the users personal inventory is for sale. Additionally, the user will be able to catalogue and chart and print in various ways the items in the users personal inventory, compare the users overall inventory to other users, and view sample images of items in the checklist or that of other users. The personal inventory aspect of the website I expect to be free however to be able to perform certain other functions such as sell an item from the users inventory, the user will need to make a payment to the website and provide funds into a personal account specific to that user. Therefore I will need some way taking credit card payments. Similar to an e-bay auction, it will be necessary that automatic messages be created to users in the event that an item a buyer is interested in contacting them. As the administrator of the web site, I must have the ability to add to the database of items in the various categories for users to check off whether they have in their inventory. It is also necessary that I have the ability to track a user account balance. Please consider that my budget is limited, however this project is not immediately urgent. Additionally, I would be open to suggestions of how a beginning phase of the project might be made such as the inventory aspect which would allow me time to populate the database while the e-commerce capability is left open to be expanded upon at a later date.