Comment by danpalmer

That's fair, but many of them may also prefer to see the money spent on the service (or other marketing). If I was paying $20 a month for a service on the basis of creating a sustainable paid search business, I think being sent a "free" t-shirt would call into question the sustainability and make it harder to justify the cost – can I pay $15 for a service that doesn't send t-shirts?

More generally though, word of mouth is a good place to start but it maxes out quickly, especially for niche products. There will need to be some support from other channels. Even just putting the name of the company on the t-shirt would have supported it a bit.