I'd buy them now so you can enjoy them..... . just pick them up used
if you can get a good deal..... Go for it.....
EDIT:
also... people avoid DVDs like the HIV.... I don't get it.... DVDs still are capable of a very nice picture... and good sound. Sure there are some turds out there too, but as far as content goes, Hitchcock movies are very re-watchable, and I'd pick them up unless you have heard any rumors about their future releases, which I haven't.......