Patrick,

First, you probably DO NOT need springs. German steel is among the best. Measure the static height of the car and compare it to specs.. If it is close to the right height, then the springs are fine. They will not hold the car up if they are weak.

Bottoming is usually bad shocks as you suspect.
Contrary to what I've seen posted here, you can get a decent set of Monroe struts for about $150 for all four from Wrenchhead.com or carparts.com. They are not bad shocks. In fact their newest line "Sensa-Track" is their line of "World-Class" shocks and are made to compare to Boge/Sachs?Bilstein.

You can get a full set of Sensa-Tracks for around $250, but quite often the web sites run promotionals for 1/3rd off of that.

Konis are lifetime shocks and are adjustable from somewhat firm to bone jarring. As the shock wears a bit you can dial them back to your desired stiffness. They are VERY expensive, but they last forever.

I would personally stay away from KYB. They are stiff, unless you like stiff.

Boge are great shocks, and give a better ride than Bilstein, yet control the car just fine at a lower price ($250/set).

Installation prices vary. Some shops almost install struts free if you buy the struts from them, so I'd call around.

I just did a set of 4 and I HATE the job as I don't have hydraulic strut compressors. If you're handy, however, and rent a spring compressor, it is possible to do the rears in 2 hours and the fronts in 3.

Order a set of bump stops and dust boots as if your car has been bottoming, they are most likely toast.

BE CAREFUL if you do them yourself. Get a good manual ( your suspension resembles the e12 chassis). Compressed springs contain enormous energy.

Bob