CKG

I have a Honda odyssey 2009. While driving it pulls to the right. I noticed this a while ago and got wheel alignment done and it did not fix the problem but was better. But now it has become worse. I took it for wheel alignment to a non dealer mechanic and was told that rear camber is off and need to install adjustable arm to fix it and quoted around 600 dollars. Want to get some information from anyone who had similar problem and got this done? Is $600 reasonable for such fix.

thanks in advance