It was in the top 100 for a couple of days awhile back (right after the Amazon price drop). It's stayed steady in the top 300 ever since.
Considering that Fox has given this box virtually no promotion (none nada zippo) it's amazing that word of mouth has carried it thus far.
Had Fox released this a week or two earlier, it might have picked up some additional sales related to the Father's Day holiday. As it was, they released a box set of Betty Grable musicals this week.
Sales should begin to really snowball as the set becomes available. Watch for the DVDs to pop up virtually everywhere, including on eBay, where I have already seen some "pre-release" sales. The MGM "Chanthology" - Monograms - continues to sell well to this day, two years after its release. Just think how well these quality Fox Chans should do...