Why aren't ISPs providing stratum 1 NTP service?

It seems to me that the days when running a GPS refclock into an NTP server
was exotic are long past. Why don't providers give NTP stratum 1 service to
their customers? Then I can at least shed some of the most suspect clients
(it's the routing path not the user that is suspect.)

In search of good time for all,

  I looked into setting up a WWV based refclock a few months back for a
client. We were unable to find a WWV capable clock for under a few thousand
dollars. The old Heathkit one ($300 or so?) was no longer available and all
of the other ones I found mentioned in the xntp docs were in the thousands.

  You mention using a GPS clock, while I've been looking into WWV. Can you
point me to some, hopefully inexpensive, hardware that we could use to
provide this service?