Be patient (if you don't have the funds right now), wait a little longer and save the $$$ to get shocks along with the springs. Or do a LOT of research on here (there are hundreds of threads) and read about every setup. Suspension is not something you want to sacrifice with this car. Trust me, you'll be sorry if you just change the springs and not get shocks at the same time. And you don't want to have to go back and do them later. Get it done right the first time.
And don't let someone do this for you. It's not complicated AT ALL. And if you're not happy with it or you end up with anything loose, you can do something about it yourself.
I'm on my 3rd suspension with this car and I'm far from a mechanic. I can't believe I EVER let anyone do this for me.
In the process of restoring an 07 335i