How much should I pay for starter solenoid?

[Rolex Snob]

I started my car this morning and it died out in a wierd clunk noise. I went to restart it and it acts like it's trying to turn but making a different noise. Instead of a whirring cranking noise it's a constant startup whine (straight tone). The only thing I noticed is that my coolant low light came on while driving home last night. I finished the 45 mile drive home and called my dealer to have it checked.

I checked my coolant just now and it looks as if it is bone dry; wouldn't the engine overheat? I made sure to keep an eye on the temps while driving home last night and all was fine.

I am hoping my engine isn't locked up but surely the computer would let me know if that's the case. Then again this is a BMW, I don't trust anything electronic.

Any advice? I hate waiting a day and a half to hear from the dealer...it's the worst.