I picked up a used P220 a couple of years ago of about the same vintage, I believe. I sent it back in to Sig to have all the springs replaced and night sights installed. They were running a special at the time, as I recall it was around 100$. They inspected the pistol and found a crack in the slide, it was replaced at no charge to me. So, I got new springs, night sights and a new slide for around 100$. I looked it up and they now charge 144.95. I figured it was worth it just to have the gun inspected and the night sights installed. It appears the inspection with spring replacement without the night sights is 89$
http://www.sigsauer.com/CustomShop/SSP.aspx