I picked up a P6/P225 a couple of months ago. It was definitely zeroed for the previous owner and did not shoot point of aim for me. It also had a weird combo of sights (numbers) on it. It wasnt a big deal for me, as I was going to replace them with night sights anyway.
Top Gun Supply is the place to go if you want parts, or anything else for your SIG's. I picked up one of the new spring kits and a couple of new mag springs. I also got a new, P225 mainspring. The P6's DA trigger is heavy, and not like your normal SIG DA trigger. The P225 spring corrects this.
Top Gun also has the SIG armorers CD, which is a must have. Its the best $20 I spent.