Boxerworks.com

As for parts - mail-order seems to be the norm, these days.

Matt, the guy that puts this forum on the internet, has a business selling used parts, and he has just reopened for business on new OEM parts as well, it seems. http://boxerworks.com/imarket/

I also like Hucky's in Florida - http://www.bmwhucky.com/index.html
He has the real, copper, crushable crush washers for all your drain and fill plugs.

Max BMW is good: http://www.maxbmwmotorcycles.com/fiche/fiche.aspx

Chicago BMW is best on price, but call your order in and verify what you want in in stock, or it could be a long wait: http://chicagobmwmotorcycle.com/store/

In England is Motobins: http://www.motobins.co.uk/ They have good prices, some things not typically available elsewhere, and decent shipping on light items - both in cost and time.

My favorite for exotic reproduction stuff is S. Meyer in Germany, with very good service to the states: http://www.meyer-bikes.com/home.php

And don't forget RealOEM. I don't know if this site sell parts, but it is my favorite online microfiche source:
http://www.realoem.com/bmw/

Oldsoul70...(does this mean you are 70?)
A couple of years ago, a fellow named Jeff (BrownHornet) rode from the state of Washington all the way to Clemson, SC on a 1973 (?) R60. Then a while later he rode it back out there.
Unfortunately, it was at a shop and they had a fire, so the bike got ruined. Anyhow, if you can find a bike that has been running recently, you will be pretty well-off to buy it.
Join the Airheads...they have a website. Perhaps you can find some fellow-airhead fans nearby in their "dAIRectory", a list of members who are airhead owners who have volunteered to help others.
I see a fellow named "Dwight" in "CDA" who is at 208 769-4847 who is an Airhead. Try a call.
The monthly newsletter of the club also has a listing of bikes for sale where you can get a notion of the going prices for something from the 1970s.

Hi Oldsoul,
My '74 R90/6 sat in the barn for 20 years until I drug it out 2 years ago. I wouldn't be afraid of an old, running, survivor, unless you are planning on lots of miles. I'm sure mine needs all kinds of other stuff done to it, but for putting around it does just fine. Look in the gas tank and see what crud lurks there. From what I've seen on ebay, craigslist, etc., I think BMW's are the best buy for old, cheap motorcycles.
I really like doing business with Hucky, but for me, email is the best way to communicate with him.

Thanks for all the responce! Well I'm still leaning into this R100 deal. I didn't mention this before but the cool part of this is I've been able to do some work for the owner of the bike and have about 50% of the price worked off in labor. He'll pay me if I ellect not to by the bmw from him but it feels a little better than paying it all out of pocket. I have the parts links saved for future refrence and I'll look up Dwight in CDA. Is the airheads membership pretty cool or is the $25 better spent on a couple tanks of fuel?

Airheads: You'll get a monthly newsletter with at least half of it devoted to tech tips where a knowledgeable individual asnwers questions. You can make these into a book.
Also you get a directory of other folks of like mind who are willing to help you if you have *trouble on the road...and there are Rallys, and tech days at various member's houses where you can have a good-ole time.
(*with the MOA, you also get such a book, but the people in it are not always a big help if you happen to have an old bike...Most Airhead people keep a bunch of various spares or know where to get what you need. New-bike people may not have this)

You can't put a price on good advice and a good network. When I land this deal I'm signing up