Maybe. Totally depends on condition imo. Sigs and the "Nitron" finish used don't wear very well in my experience, but that doesn't mean it won't function perfectly nor be a super accurate weapon. You're in the ballpark but if it's only "good" condition, I'd probably not go over $475 to 500.00. If it looks almost brand new, take that deal.
And before the nomenclature police stop you and arrest, you want to call those bullet holding thingy's in the butt magazines, not clips.
Condition is the driver, look for any rail wear, not good and really can't be undone. W. German triple serial number marked pistols with the box etc do carry a premium. W. German will have the German proof mark and the serial number on the barrel, slide and frame, all matchin
The 228 is my favorite pistol, best luck and if you get her, you will love her.
If it's a German gun in good shape it's worth $550. I watched one on gunbroker several weeks ago sell for $570 with nothing but the gun...not even a mag.
Blowing the pics up looks like the slide is serial numbered, the barrel is numbered on the left side so you can't see it unless removed from the slide.