Hard to say without a lot more detail. Use a stamp catalog, usually available at your local library, to identify the exact stamps you are looking at. That will allow you to get an estimated value and see if they are worth taking to a dealer.
It is worth the cost of the stamp.
how much did a postage stamp cost in 2016
About $2.00
Most stamps will show the value of the stamp somewhere on the design.
a stamp in Montana costs 44cents
GO ASK ARGENTINA
44 cents per stamp
I have the stamp in good condition. It was for 15 cents.
Check your stamp at the link below.
The E stamp had a picture of Earth on it. The face value of the stamp was 25 cents.
There isn't any stamp that is called a penny purple. You need to describe the stamp - include country and if you can date and what is on the stamp.
Without knowing which stamp, it's pretty much impossible to value.