In keeping with the slew of promotions around Thanksgiving — Cyber Monday, Black Thursday, Cyber Black Friday (no, that’s not us mashing together buzz words, it’s a real term) — Twitter plans to celebrate “Small Business Saturday” by giving as many as 10,000 businesses $100 each in free advertising. It seems to be a generous promotion. But can it work for you?

Twitter is famous for not publishing rate cards. If you go to their advertising page, you find a standard solicitation form. This is because twitter’s ad services — promoted tweets, promoted trends, and promoted brand pages — vary greatly in value, depending on what’s being promoted and where. Promoting specialized cupcakes in a small, two-block area may cost next to nothing, while promoting a “Vote Romney” message across America can cost up to $120,000 a day.

At this point, one might wonder “with services in the hundreds of thousands, can I really get real value for only $100?” The answer is a definitive…maybe.

Twitter points out that many small business have used similar $100 credits to build up hundreds of new customers quickly. Most of these businesses though are located in high-density areas. One bakery cited, for example, was already in a wealthy district of New York City, an area with a population density over 27,000 per square mile. Promoting “fresh baked cupcakes” in even a small block of New York City would therefore reach tens of thousands of potential customers. Similarly, small businesses that appeal to very specific groups of clients (say, customer-built floating playgrounds at $70,000 apiece) might also be able to take advantage of this free advertising. Businesses in this line are reaching a tiny pool of potential buyers, perhaps as small as hundreds. Paying for access to those feeds in this market niche would be relatively inexpensive, but could reap hundreds of thousands of dollars in new business.

Consider your business. Would it be able to take full advantage of a $100 dollar credit on Twitter, or would it require a much larger investment? If so, how much?

One thing is certain: Twitter’s rates have increased by as much as $30,000 a day over the past year. As we’ve seen as recently as this past election, politicians have been able to change elections through Twitter. And if anything, Twitter’s prices will only increase with the recognition of how powerful the service really is. If you’re choosing not to advertise on Twitter, it shouldn’t be because you think it doesn’t work. It should solely be because, at this time, it can’t work for you.