they are mounted straight into the strut if i am correct.alignment isn't affected by a sway bar link change. Anyways, I've done them myself on lots of cars, these ones look just as easy. They are so long?! What's the deal with that?
I've seen some aftermarket ones on ebay and on FCPGroton, but you won't get any performance out of them. It's always the ball joints that wear out due to contamination. You can increase the effectiveness of the front sway bar if you lengthen the sway bar link or make the link thicker. I think the car understeers and is stiff enough in the front IMO. There's no need for such a modification. If anything, I had custom endlinks made on my previous cars by using tie rod ends which have much stronger balljoints with less movement. They last forever!
I haven't really checked, but are our sway bar links moutned to the front struts or the control arms? It's more effective to have them mounted at the strut. There's more leverage. If they are mounted to the control arms, you can have tabs welded to the strut and mount the endlink to the strut instead. This is a common practice on track cars. I've done this to my previous M3 as well.