I may be wrong here, but I think that "SIA" refers to the company, Special Interest Arms:
http://www.specialinterestarms.com/index.php
Serb
Yep thats them. Looks like a nice numbers matching G kit built on a FEG receiver from SIA in NV. I feel good about this one so it's now mine. WASR's are up to $549.00 locally so I think $500 was a good deal.
$500 is not a bad price at all given today's market.