Have you looked into getting the parts yourself to maybe save some money, and upgrade at the same time? Find out if they will put parts you purchase on the car, then see if that makes more sense. Or, you can change the pads yourself for like 60$ (if it's only the front or the back). Maybe you can have your rotors turned instead of replaced, then replace them next time.
Cross drilled front rotors for a '98 e36 for 170
Front pads for same @ 55
Sensor for same @ 10
Total - ~240$ for parts.
You tell me, are you getting ripped off?
<span style='color:green'>Nobody likes you.</span><img src='http://www.bmw-forums.com/forum/html/emoticons/ph34r.gif' border='0' alt='user posted image' />
<span style='color:green'>Are you experienced, little girl? I want to know what goes on in your little girl world.</span>
<span style='color:green'>I'm the man! I'm bad, I'm so bad I should be in detention. I'm the man!!!</span>