Similar to the Solonav Creator, the Solonavi Siren is a non-Unique figure. Thus, it's cheaper- maybe a buck or two to buy one.
Game-wise, it's fairly useful, although not as uber as the creator I reviewed earlier.
The sculpt, though, is gorgeous! On par with the Creator, it's not as good as the Tormentor (I'll review that little one later), but the transluscent plastic effect, and its pose, are incredible! This picture does NOT do it justice!