A Sig dealer told me it was going to be $125-$150 extra to have the mag release on the right side of the pistol. Because from my understanding all P226r come with the release on the left. But my Brothers P220 is on the right, he got it used and it is probably older. Is this normal that I have to pay $150?
You can reverse it yourself. It’ll only take a couple of minutes (though you need to do it carefully!).
See here: www.ar15.com/forums/topic.html?b=5&f=14&t=18755
Again, don’t get in a rush and scratch anything up, or send any springs into low earth orbit, or incorrectly insert the mag stop catch.
Read the above thread, use a plastic bag, take your time, and you’ll be fine.
ETA: Oops! Here’s an even better thread: www.ar15.com/forums/topic.html?b=5&f=14&t=19231