As far as the value of secretarial signatures, some do have value. It obviously depends on who the celebrity is and the time period. A secretarial signature of more current stars is likely to have no value.
However, a secretarial signature with a fair amount of value is the Babe Ruth Sinclair Oil contest signed baseball. Though winners initially thought they had received a real Ruth autograph, it turned out that all were secretarial signatures. Yet depending on the condition of the ball and autograph, I think they typically sell for $300-$800. But that's because they are related to Babe Ruth, and they are historical.
JFK secretarials also have some value. Having said all that, I don't know what the price, if any, would be for a Reagan secretarial.