I think it's a little high , but don't have a recent reference handy , I do know Libertads sell at a good premium though . I will ask someone who keeps up with these though . JMHO
40 is full retail. source, 2011 North american coins and prices. Remember 2011 silver was marching up, the same book has the 96 ase for 47 and I have been seeing them around 35 lately.
Most dealers I know don't recognize too much of a premium on these. I usually pick these up, even the good dates, for $22-30.
Depends what you mean by "average condition". If it were in the same condition as the coin you posted, then almost 3x what the 1999 goes for.
Here the mintage and history. Libertad (coin) - Wikipedia, the free encyclopedia Sometimes the 4 coin set worth more than a 1oz and Not due more pure Silver. Mintage also grade is also a conversation