mike wrote:

I'm looking since a long time, a compagny that sells surplus microwaves
doors openers (solfan modules or similar).

One possibility is http://www.shfmicro.com/ (in USA)

They have only the microwave modules, not the rest. Currently the
website shows only varactor-tuned units, while SOLFAN's are nominally
only mechanically tuned. These are more expensive than the simpler
units more commonly used in door openers or intrusion alarms. Their
stock varies from day to day.

73,
Steve VE3SMA