Auction website acceptance test creation

I have taken alpha delivery of an auction website and have a schedule of release upgrades which I will receive over the next few weeks. I need a tester who can work through the website to establish functionality, generate acceptance test cases for the entire site plus a test coverage matrix so that we can see what tests have been performed. Ideally these tests would be automated - by creating them as scripts which can be run using Selenium or other browser-based test framework. I can provide access to the development website prior to agreeing a price and timescales. For now I am looking for someone who is capable of performing this work in the next 3-4 weeks and who would be able to follow this work up at a later date (when subsequent releases are delivered) to define acceptance test cases for new functionality and, when passed, incorporate them into a full regression test suite which we can use thereafter. Successful candidate will be native English speaker, good communicator, logical, methodical, have experience of test automation (particularly Selenium) and immediately available. I do not want a company, but want an individual I can trust and deal with directly. I am prepared to pay top dollar for the right individual so that is reflected in the budget - I do not regard this is a large/long project but will pay upto the sum shown for the right individual. Please provide details of similar relevant work you have done and, using eBay as an example, a ballpark figure for the work/time involved in producing a complete acceptance test suite. I won't hold you to any quote given at this point but do want to see how you arrive at your estimates.