That gun is Sig in name only (i.e. don't think of it in the same quality terms as their pistols). Several companies have made shotguns for Sig in recent years.
Randy Wakeman has the following to say about the SA-3
quote:
When Sig Arms attempted to enter the O/U market, they just added to the confusion. The name of "Sig" meant nothing. The Zoli-made SA-3 models were very, very poor, while the Battista Rizzini SA-5 series guns were first rate. Rick Cole (Cole Gunsmithing), the Beretta King, imports some B. Rizzini's, as does Rizzini USA, as does William Larkin Moore & Company. The differences can be subtle.
I wouldn't buy it but if your friend wants the gun I wouldn't pay more than a couple hundred.