You don't need to find a complete bicycle, just start by looking for a decent frameset that fit you nicely, or get a new one, like the excellent Surly Crosscheck.
Considered it as a project.
I have an Nexus 8 speeds wheel complete with all the cable and gizmo I can see to you, the Nexus is just like the Alfine, only it doesn't have mount for disc brakes which you don't need.
You don't need to find a complete bicycle, just start by looking for a decent frameset that fit you nicely, or get a new one, like the excellent Surly Crosscheck.
Considered it as a project.
I have an Nexus 8 speeds wheel complete with all the cable and gizmo I can see to you, the Nexus is just like the Alfine, only it doesn't have mount for disc brakes which you don't need.