- BMW fuel pump is made by Pierburg. So if you can google "E53 fuel pump Pierburg" and see what you get. Be careful about counterfeit, if any.
- The fuel pump itself is cheaper, about $150.
- The fuel pump assembly is more, about $270 at dealer:
PN 16116755043:
BMW Parts - Chevrolet GMC Cadillac BMW Mercedes Benz Parts and Accessories
- Fuel Sending Unit (Driver's Side) is PN 16116762044, about $85.
I understand you have the itch to replace fuel pump b/c of the mileage of 150K, but the car runs fine, so I'd leave the system alone for now. The sticky sender unit is a well known problem and Techron usually fixes it.
Anyway, best is try Techron and see what happens. Most fuel pump failure happens people allow fuel to run dry (less than 1-2 gallons). If you never let the fuel runs below 2 gallons where the pump is located (this means "above 1/4" in BMW with "failed siphon pump"), the pump easily lasts beyond 200K.