First, and most importantly, the grade on the holder, regardless of the holder type, is no set indication of value or predicted selling price. We all wish it were easy enough for us to determine a grade and then determine the value, but in the real world it just doesn't happen that way, more times than not.
You can often look at the major selling sites that many of us enjoy, such as Heritage Auctions, Great Collections, and
ebay, and see huge ranges for the "same" coin. It might be listed as a 1934
Peace dollar graded MS-64, but the resulting prices can sometimes have huge differences for this "same" coin.
So before I go further it is important to know that a given date at a given grade by the same
TPG, sold near the same time, will not necessarily result in similar prices. There are a number of reasons why, which could easily fill a whole book by itself, but let's move on to your real questions.
You are perfectly capable of answering your own questions with the plethora of details available about the
Peace dollar series. I understand your interest in learning from others and you are correct in having some hesitation to jump in to such a potentially expensive set without asking questions. But you will learn so ever much more yourself if you do the necessary grunt work of looking at those available numbers with the goal of them teaching you the best possible system of evaluating most coin values.
First, don't assume that what I'm saying is correct. You have the tools available to check to see if what I'm saying is based on facts, or a fond memory, or utter idiocy. As to the discussion of PCGS versus NGC, let's look at some actual numbers. NGC has graded a total of 713,031
Peace dollars while PCGS has graded 580,710. To establish if one or the other has a tendency to over grade, we will assume (and I know that is sometimes troublesome) that both receive about the same general quality of grades for any particular date/mm.
Here is the important part. Does one or the other certify at a much different level for the most common grades from 63 to 67? I'll now list the grade, followed by PCGS percentage first, and NGC percentages next. 63 - .38/34; 64 - .36/393; 65 - .078/0909; 66 - .0128/0124; 67 - .00045/0005. Looking at these numbers we see that both are nearly identical for 63's, NGC has an extremely slight tendency to grade a very few more 64's and 65's on average, with almost identical percentages on 66 and 67. Looking at these numbers with a long view shows that even these very small differences are far from any type of proof that one is much different than the other, overall.
As for price, I took 3 date/mm and compared them to actual sales on Heritage Auctions, listed in Most Recent order. I insured that I did not include anything with a star or a + in this examination. Both had a few CAC but that did not always increase the value, by any means.
1921 MS 64 - PCGS High $881, Low $540, Average $671.NGC High $1057, Low $646, Average $808
1928 MS 63 - PCGS High $593, Low $399, Average $552.NGC High $705, Low $591, Average $636
1934 MS 64 - PCGS High $282, Low $235, Average $258.NGC High $329, Low $282, Average $297
Keep in mind that these are only three date/mm at a specific grade point, but these figures, which can be checked from the Heritage site, certainly indicate that NGC, not PCGS, averages higher sales prices.
Last - I would strongly suggest that you take your want list, carefully examine that average sales prices per grade in the area that is close to your desired monetary expenditure, and stay close to those grades as you find them. In other words, the 1921
Peace dollar sells for around the $350 mark as an average for MS-63, while there is quite a jump to $750 average for the MS-64. These differences are strictly because of the number available, in most cases, with the big jump coming because of the much smaller number of 64's that have been graded.
Find out where your grade average is at, and try to stick to those goals. You don't need to pass something up if it's too good to miss. I've went both above and below my anticipated want list grade when there was a good reason to do so. Just remember the first thing I mentioned. Prices can jump quite a lot for the "same" coin in the "same" grade from the "same"
TPG sold near the "same" time.
Registries are great ways to help you keep goals. Unless you are a big buck buyer you won't earn many 1st spots, but it is fun to see your numbers increase as your collection grows.