Web automated script based tests

Have a website which requires some automated tests to be created. Goal being to simulate a user performing common actions such as adding a product for sale. Our site uses a customised Wordpress site - PHP, MySQL etc. Addition of a product for sale takes the form of supplying some text and images on a series of screens. Think something like listing an item for sale on eBay and you're pretty much there. Details will be given to bidders who demonstrate the necessary skills and experience. Key goals: 1 - Write a script which simulates the actions taken by a user to add a product for sale 2 - The script should be modifiable 3 - Resulting data should have an element of randomness (we don't want to end up with hundreds of exactly the same entry) 4 - Must be able to run the script a defined number of times. At least 1000 5 - Easily populate our back end database with 100's, 1000's or 10,000's of entries 6 - Use an existing package rather than hand crafted scripts. 7 - The tool used to create the automated test should be preferably web based, preferably free or a low cost. Use of LoadRunner and other tools costing hundreds/thousands of dollars is not suitable To be successful please ensure: 1 - You detail your experience in this field 2 - Tell me what tool/s you plan to use 3 - Convince me that you can deal with tricky challenges around automating the user tasks Success criteria: 1 - A working script 2 - The script should be easily modifiable 3 - Basic training/support on whatever tool/framework used to create/execute the script 4 - The script needs to populate our database with 10,000 entries