If you can source the handles (they were standard on every E90 from SE up) so should be out there then it's just a matter of fitting and connection to the doors puddle lights.

I think you can even just buy the small stubby bit with the LED in them as a few E60 owners have done this as a nice little upgrade. I'm guessing your car is an ES though, so you may need to check that door has puddle lights or wiring for them.

Mick in Germanicks would put you right here I would imagine.