Here's another shop in Austin, TX, that specializes in manual conversions (no affiliation):

http://www.terrysaytherauto.com/Home.htm

They currently have an e34 535i donor car and will put together a "kit" for $1350 + freight, which is a pretty good price. The 6-spd trans is quite a bit more expensive. Good used Getrag 260/6's sell for $500-$750. A good used 6-spd S6S 420G sells for $1500-$2500.