A quick search shows Lake, Shimano, Louis Garneau and Pearl Izumi all make size 50 shoes. Will they fit ?, you have to try them on. Some manufacturers are sized small, the Lake winter boots I just purchased are a 47 when I use a 46 in Shimano. I'd do the research from these companies, add in Mavic, Giro, Specialized as well. Than find a good LBS, see if their website lists inventory, etc... and pay a visit.

Note that it's a crap shoot buying shoes via mail order as I discovered with the Lake shoes I purchased. I typically go to the LBS for shoes.