Way back when I wrote that, it seemed all that had been announced was the 8 speed version. The less expensive versions came out after.
I don't know why the 8 speed version is so expensive. While the 8 speed hub is new and more expensive than the three speed, it isn't that much more money.
Modern internal hub gears are practically no maintenance. This includes SRAM and Shimano. I haven't dealt with any Sturmey Archer hubs less than twenty years old. Back in the old days, they had oil ports where you would periodically put a few drops of oil to keep the gears working. The old Sturmey Archer AW hub has a reputation for being nearly indestructable. These days they're all greased. Presumably, one day it's possible to need regreasing (after LOTS of miles). More likely, new brake shoes (for coaster brakes, usually after LOTS of miles). For generally flat terrain, this means they'll last practically forever.