So, from what I am going through, its not a cheap conversion... I am in Finland so taking into account the prices here
Cantcu, flying lead connectors: 1470 euro
8hp50 box: 480 euro
propshaft : 700 euro
domiworks adaptor: 1500 euro
G series shifter: 35 euro
Oil cooler 60 euro
I have had the prop made using an E60 530d one with a ford end for the diff

I have still to make up a rear crossmember and find a place to mount the oil cooler and lines.
Other things to take into consideration....you need to mount the shifter and cover the hole where the gearstick came through into the car, but allow the gearbox wiring to pass through. And then you need to make a trim piece for the centre console.
then there is gear display to think about and what are you going to do with the speedo and how are you going to measure the speed.

I am putting an AIM PDM32 into my Escos with a 10"dash, so can have the speedo and gear displayed on that.
I have just ordered an MK60e5 abs unit from an E92 M3... so now looking at putting that in the car.
I picked up a wireless shifter kit from Australia, so will see if I can integrate that for paddle shift.

Its not cheap, but the adaptor and tcu is the most expensive part. I think Maxxecu can control it, so if changing engine management then that would probably offset the cost a tad.

It wont be everyone's cup of tea, but I am doing it for me, making gear changes 100x better than the shonky T5 and heavy clutch that I have just now. I am trying not to have to make any unnecessary holes or have any extra bits welded to the car, this way it is all easily removed and put back to either 4wd or rwd should I ever sell the car in the future.