Bant Eldrazi is picking up steam as a Modern deck, and much like Adarkar Wastes before it during Eldrazi Winter, the painland of choice for the deck is seeing price growth. Specifically, the Tenth Edition printing is disappearing from the internet.
At the time of this writing, there's one LP copy on TCGPLayer for $8 and every other copy is listed at $19+. I would expect the new price to be closer to $8-10 than $20, though there is definitely demand for Brushland that there wasn't before. In particular, the Tenth Edition printing is one of two printings that is black bordered which explains why it would be the most popular printing.
The other black border printing is from Ice Age, and they don't look particularly nice. That said, I know that I generally prefer the original printing of something and I'm not alone. Further, if the Tenth printing is going to be significantly more expensive, then it would make sense for players to purchase the Ice Age printing instead and move that price. Currently you can find some Ice Age copies for about $6, and I like buying at that price. Should the deck continue to gain popularity in Modern we should see growth in every printing of the card.