adding cruise control, help

I'm a new bmw owner just bought a 2000 Z3 which is stripped. Want to add cruise control to keep my foot out of trouble. Have checked several dealers, no go. Aftermarket installers, no go. Emailed bmwusa = they gave me a part # and said the part will work. They also said msrp is $119. However the dealer wants to charge 139 - 159 for the part??? Hello, i told them what was quoted was the msrp not cost from bmwusa, their reply was this is our price. Installation labor & material quoted 375 - 550. One tech indicated that is could be real easy if bmw installed all the wiring already..

Any experience in installing cruise control / suggestions?
Any other source for bmw parts
Recommend a good tech book for the car??

thanks in advance for your help,
Quinn

I don't know any specifics about adding Cruise control to your Z3 but I have found out through my own suffering that the cruise control in tied into a AUX module for the overall engine/car control. It is not a self contained accessory. My traction control, cruise control and check engine light all failed simultaneously. Engine codes revieled Crank position sensor and Aux I/O. I replaced the Crank snesor and it did not fix anything including the now poorly running engine. My advice - pay the man.