Awesome! thanks for all the information guys. I spoke with David and he told me it was going to cost me $550 if I sent them the valve body so I should probably check with Kirt, he might have a "bimmer.info members special" or something.
About getting the part out; I recently rebuilt a Jeep Cherokee's engine in my garage without previous experience (just for fun), and I was able to put it back together and it runs so I think this might be something I can try. Besides, David told me he's going to send me some literature and diagrams showing how to get the part out.
David also mentioned that they have the original fluid from BMW so I guess it's the best option.