Apache PHP Point of Sale Software

We currently have a online order entry system for an eBay drop off location. We require updates to the software in PHP in addition updates to the MySQL database. We are looking for someone who can either take on phases of a project or do ongoing upgrades to the system. It can be accessed through a SSL secure web address... it may be beneficial if you have your own development server with Linux and Apache Server so you can develop this locally. We have a requirements document with needed updates and changes to the software, some of the changes look are simple and there are a few complex changes needed. Examples... 1.1.35 [AAPHIV-31] Add date email sent on item status -> List all items to be donated/returned 1.1.36 [AAPHIV-32] When we relist an item, we don’t charge the customer for the first listing fee and second listing fee. Now if the item does not sell with the second listing we offer the customer to relist a third (fourth, fifth, etc) time for $10 per listing. Can we figure some way to have the $10 fee charged? We would replace any fees in the Commission Prepayment with this fee. 1.1.37 [AAPHIV-33] Allow the creation of duplicate invoices for existing items. When we do a search for an item like in req 1.1.24, an option would be listed next to the invoice that allows us to make a duplicate invoice as long as the customer is already entered into the system. (would this be the best location for this?) Also, the option to create 1-20 copies defaulting to 1 copy. So I could create 15 invoices from item #2533. We are currently in a speculative mode right now deciding if we want to develop further, any comments on your part may help us decide on how and what to do with this project. It may be an ongoing project with changes implemented all the time, or we may do the project in phases.