I paid $190 as a doc prep fee on my 135i exactly 30 days ago.
Edmunds.com has this to say:
Doc fees: In states where doc fees are not regulated by the government a dealership will often sell a car at a very attractive price but then hit the buyer with a $399 doc fee when the contract is drawn up. If you refer to our chart, and see that doc fees are not capped in your state, you should find out early on in the buying process what the dealership charges. If it is high — anything over $100 — you will need to negotiate more aggressively to offset this price.
There is a chart on this page:
http://www.edmunds.com/advice/buying...4/article.html
I'm not sure how accurate it is. I paid more than the chart says I should have, but I'm not about to argue about $29. My dealer threw in a substantial gift certificate about a week after the deal was done that more than made up for that. Way more.