Basically after doing so much reading on this I decided to have a go DIYing.
I have purchased walnut media and related equipment and borrowed a compressor.
Nivedh and I will be giving this a go tomorrow and will report back on how easy/hard it is and costs associated.
Depending on how it goes we might be able to do a few more cars but it won't be tomorrow.... Tomorrow is for muddling through the first try!
Ill take a bunch of pics and try put together an idea of what it entails also.
2008 E92 335i