Graphic Design for Landing Page for PPC Campaign

This is a small project for a freelance graphic designer. We need a design for a single landing page that will be used in a PPC (pay per click) campaign. We are interested in finding a freelancer who has tested a variety of graphics and layouts for "sales letter" landing pages. By "sales letter" we mean the typical one page piece that is reminiscent of "direct marketing" (or what was junk mail in pre-Internet days). The page will include a headline, lengthy sales copy, customer testimonials, a guarantee, and a "buy now" button. You must have extensive experience with split testing (A/B testing), measuring conversion rates, and assessing the effectiveness of graphic design choices in terms of conversions from visits to sales. Ideally, you can tell us whether green or orange makes a better color for a "buy now" button, whether Ariel or Times Roman results in higher sales, and whether a testimonial should be placed in a sidebar or displayed as a callout in the sales letter. Please introduce yourself and email a list of URLs to the address below. We're not interested in links to your general portfolio; we just want to see "sales letter" pages you've designed. We want to see that you've designed landing pages for Internet marketing sales offers. PLEASE, if you bid on this project, DO NOT send private messages (no PM's!) as we are too busy to read them all and we will only read your actual bid entries.