Sample slabs with Morgan and Peace dollars are common and for sale on ebay all the time.
PCGS has the 1921 PDS Morgan and I have only seen one 1923-S peace dollar for sale.
NGC has lots of both dollars in the sample slabs. I have even seen them graded MS-60 with a green CAC sticker, Don't know why they were not gold stickers, I guess just beat up dollars in the holders.