Advertising is the lifeline of your business. Cut it off and your business suffers, (unless viral marketing kicks in, but that's another story).
Unfortunately, advertising is not always cost effective, especially in the early stages of your business. You can try other ways to get good advertising besides paying for it, such as:
Write articles and submit them to publications that cater to your target audience.
Send out a press release and get some free publicity .
Barter products, services or your expertise in return for advertising.
Create an affiliate program that will allow you to pay commissions on sales made.