I dont know where Sigma Pi gets our run of the mill pledge pins from, but I work for the national headquarters of Sigma Lambda Beta and Sigma Lambda Gamma and they get theirs through Burr Patterson and Auld.
The SLB/SLG pins are adequately detailed, nothing extremely fancy, but I believe they do custom designs, and they arent too badly priced.
I think a pin if you do a run of 50 is about 6 dollars each. Larger runs cut price im sure. Custom design probably costs more for first run too.
They also do nicer scale jewelry pins, you know the full out jeweled designs, ive seen some of their designs and they are good.
You can contact burr patterson and auld at:
www.burrpatt.com