Tourna's newest tennis string is the Big Hitter Black 7, a co-poly (meaning a blend of poly with other elements) that is shaped with 7 sharp angles which bite into the ball for what Tourna calls "massive spin production." I'm hearing it recommended for higher level players with a strong baseline game.
"This new Big Hitter Black 7 is pretty cool," said playtester, Jonathan. "It's very elastic for a poly - which gives it comfort and pop and dwell-time, but it also has the spin, control, and durability of a poly. It bridges the gap between poly and multi in a very interesting way, IMHO. I really like it. I knew I'd like it from the second I did the elongation test on it."
MAP is $8.95 for a set (enough for one racquet). Take note, In the world of tennis string, that's a great price; worth a try for sure if it's got what you are looking for.
Tip: If you've got any elbow issues, best to avoid or string more loosely.