Doing a quick google search for Mobil 28 grease which is a MIL spec WTR=Wide Temperature Range aviation grease yields $15.00 U.S. for a grease *** cartridge. It works and is approved for Boeing wheel bearings. Hope this helps. I will add if you stop and think about it if you got several years out of 40 euros is that a bad deal?
Cheers,
David in Alaska