Along with @atcarroll 's eBay results, the thing about APMEX is that (sometimes) the photo is a stock image, and not the exact coin you'll receive. You'd get a Morgan dollar of the year, mint mark, grade, and by listed grading company, but not necessarily the coin/slab shown. Also, PCGS slabbed coins tend to sell for more then NGC/ANACS/ICG coins, so that could make up a portion of the 'premium' you talk about. The other 3 aren't bad, or bad graders (they all make mistakes), but the market deems PCGS to be more desirable.
Oh, and on a side-note; Thanks for actually listening to the members here, rather then become defensive and obnoxious. We are all here to learn, and to help when/where we can, and nothing is more annoying then a new person thinking they know more then they actually do. So, welcome to CT, and I think you'll have a great time here!
If the coin is in a plastic bag as you have shown here, pass. Don't feel obligated to buy. Go in, talk to the dealer and look at his coins and the prices on them. Read and educate yourself. Find an area of interest, such as Morgan's and Peace Dollars. Learn what you can about them and start off on lower value coins or buy slabbed coins. The top 3 are PCGS, NGC and ANACS. I've never bought anything off of eBay but a number of members do but experience plays a large part in buying. David Lawrence is a well known dealer but I've never bought from him as I think he's on the higher side. Stay on CT and watch the threads about value and other areas of interest. We do have a weird sense of humor but you can learn a lot as a member.
If you want to see about what coins are worth, check out the archived sales on www.greatcollections.com. Great place to buy with nice photos and the auction house has all the coins and it is a true auction.
Thanks!! Great lead. I had a lot of fun on that site and won an auction. Nothing exciting, but now I at least have an example of a graded ms62. Man, this rabbit hole goes pretty deep.