I definitely understand about it being difficult. One thing to remember, most people who collect or sell coins are not experts about
Sacagawea dollars. If you spend $50 having it 3rd party graded, it will probably be the best $50 you've ever invested. Just take the necessary time and it will pay off.
The area to focus on is the shoulder right above the date. Read the article in the link below:
http://www.smalldollars.com/dollar/page20c.htmlIt will tell you pretty much everything about this coin. There is a picture of the obverse die marker (lines from polishing the die). I'm guessing it will be pretty difficult to get a good picture of it through the plastic, but you can try. Assuming it has the die marker, my suggestion still is to have it 3rd party graded.
BTW, there are very few sales of this coin. As you can see from the prices shown in the link above, the prices went down and then stabilized (though the information is 7 years old). Recent Heritage auction results that I've seen seem to be in the $4k to $7k range. I'll be glad to list them for you if you'd like.