Here're some methods that big guys have used to grow Facebook fan base. 1) For every time someone likes the page, a green balloon was blown up and placed in a office. (Heineken) 2) Like the page to undress a model wearing the company's apparel. (Stüssy) 3) Like a page to win a gift card (Vermont Country Store). More on http://www.4th-media.com/case_studies/facebook_fan.php with summary and details. Hope they will inspire new ideas that won't cost an arm and a leg.