One day when a friend was loading my Xpress on to my trailer he gunned it and the A-Arm got bent when he landed it on the tongue of my trailer. So I'm looking for a good source to buy a replacement arm at?

 

You can get a whole new kit from your dealer for around $60. This comes with new nuts, bushings, ect.
There is a metal shaft inside the a-arm, between the "ears" that bolt it to the frame. Usually this will bend whenever the a-arm gets damaged. I would pick one of those up as well, it is only $9.

You can also get aftermarket a-arms. But they tend to be pretty expensive, and you would have to buy both sides. They are stronger however. I think HPD and Hot Seat both sell them, not sure though.
I recomment just getting a stock replacement and getting a set of a-arm guards.