There are two interesting things here that point out what I talk about in my book More Podcast Money, that is, the power of your niche should never be undervalued. While it doesn't happen a lot (or better hardly ever) a sponsor may approach you if you are engaging (and have influence in ) their target audience.
The second thing I found interesting is that this sponsorship has gone on for quiet a while (being renewed every six months – hence its working for both parties). In the podcast Cliff explains that there were 59 sales in one month that resutled in five figure sales totals for the sponor.
This shows that if you match the right product to the right audience, both parties can benefit. The key is making sure the product or service matches the audience.