No selling or trading in this forum
Yep, $500 is what I came to post.
As the OP stated, no box etc, just one mag.
I've owned quite a few Sigs both folded and welded slides and stainless forged slides.
I really don't agree with all the gushing for the folded and welded slides, I much prefer the newer stainless slides. I'd go $600 if the OP's Sig was of the newer variety.