That's the X-RF8 hub, runs about $162 at Amazon
without wheel. Sturmey also has a version with drum brake (X-RD8) and a version for disc brake (X-RK8).
Those 8-speed hubs are typically more suitable for small-wheel bikes, due to the fact that 1st gear is 1:1 and the rest are overdriven.
Shimano Alfine? Ewwww lol... Overpriced junk, IMHO. But honestly, I have no experience with the Alfine line, I'd go Sturmey first