525 is a bit easier as parts are more readily available (at least, in the states) than for the 535.

But still, I doubt it would be practical. Especially if you have someone else do it for you, it'll probably cost at least 50% of what the car does. When I looked into having someone else do it for me, it was going to cost $4000+ (done by a well-known BMW expert with used parts and new wear items). Personally, I could get it done for less than $1000 and my time.

So, the choice is yours. I'm utterly stuck on my car and wouldn't sell it to buy a manual. The question is -- how irrational can you be?

best, whit