Another option for advertising is media buying or ezine advertising.
Media buying means buying adspace through specialized advertising companies. You can often get better deals than in Adwords.
In ezine advertising you are using to your advantage a fact that someone already has a list of buyers who trust his advice and therefore you can often get high click through rates for your ads - more people end up buying your product.
The trick is how to choose the correct advertisers and what to offer to get a sale. See also the free ebook on ezine advertising for some more info.