Hi! My name is Mike, and I’m really interested in your project as it is exactly within scope of my expertise. I’m a highly skilled Applications Developer, specialized in various web-automation tools. It looks like this is what you're looking for.
I’ve carefully read your requirements and can create a quality app for your needs. Just recently I've developed a very similar app for Amazon orders, and the buyer was fully satisfied. Your project is more complex, and I would not like to promise you a cheap price and unrealistic deadlines. Fully automated ordering on eBay can be quite risky, so I think you would like to control the final step of the ordering. At first, I could develop an application with a friendly interface that would reduce the ordering process to 1 click. In future, it would be possible to entrust the app fully-automated ordering.
Some details should be agreed, but generally it’s clear. I’m sure you’ll be satisfied with an efficient app, developed in a timely manner. Please, contact me if interested.
Mike