Bosch Performace Speed motor (also available as non-speed, this model name without the HS)
Gates Belt Drive
Bosch 500 power pack (also available with a dual battery setup giving you 1000Wh)
Schwalbe Supermoto 27.5x2.4" tires (signified by the GT designation, this bike is also available with 700c wheels and 2" wide tires. I prefer the wider tires for stability and comfort)
I don't think the Kalkhoff meets his < 5k criteria. And that second option, after a motor swap, likely wouldn't meet it either. I'm pretty enthused about the R&M and am fortunate enough to have a dealer nearby. Room for the large, cushy tires is especially appealing.