(and it's iso25, x-raying in the post won't be as bad as x-raying P3200).
I buy film regularly from the US and on ebay and have it posted (my local camera shop wants $28/roll for velvia....). Have never had any problems with x-rays. Looking at the ebay sellers I use (generally pbarcelon, but occassionally hotshot), I don't recall seeing any negative comments about x-rays. Not to say that it doesn't happen, but the odds of film being wrecked in the mail seem quite low.
By the way, no need to let anyone else process your B & W film. That's just lazy! Just get a change bag, a developing tank, some developer and fixer, a couple of beakers to measure liquids (ie the developer and fixer), a thermometer and a watch. The whole process will take about 30 minutes (15 to 20 minutes of real work and 10 to 15 minutes of film washing and cleaning up). And you can do multiple rolls at once. Its much faster, easier and cheaper than driving to a shop to drop film off and then going back a few days later to pick it up.