Bobby,
I don't know where much of the information above was sourced from, but here is the part number for a 95mm head/cylinder:
935 104 020 02
I have no idea what a single used unit may sell for, but here in the USA we have two good sources for new units (albeit not inexpensive): Eric Bloss from Porsche Motorsport and Neil Harvey from Performance Developments.
Neil makes his own and considers them an "upgrade" over the Porsche part. He can be reached at
http://www.performancedevelopments.com and he may have some "take-offs" that are in good condition. It's worth a fax or email.
Eric probably has plenty of used units laying around, so he may be a good source for a used unit as well if you can't find one in Germany. He can be reached at
http://content3.eu.porsche.com/prod/motorsport/sales.nsf/usaenglish/pmna_business_infopmna_personell_prjectm
BTW, his hairline has receded further.
Ralph