These vols 1 2 and 8 are just the tag end of the over-print, in other words they are remainder stock. The chances of finding the other volumes are a bit like looking for a "Bacon Bagle Bar in Bethlehem" you can look but sure as God made little apples(well we all know he did'nt) you ain't going to find them.
It is very impressive the amount of interest that good old Mudcat has generated.
It is possible to find that odd elusive vol, I once found Vol 10 of the 1882 Child Ballads from the same Bookseller in Vermont that sold the other 9 Vols to a bookseller in England that I bought. First time the hair on the back of my neck stood up when I realised what I had found in a little Bookshop in Gloucestershire. Thank you Mr Valentine