Reference frequency sources

Of interest to some folks here, an Ebay seller
http://myworld.ebay.com/fluke.l/ has many used/surplus Trimble
Thunderbolts GPSDOs for sale. I haven’t received any yet, but I heard
good reviews about that seller from someone in #hamradio on freenode.
(I purchased two, and I recommend that you avail yourself of the ‘make
an offer’ function).

Speaking of references, what synthesizers are people using to generate
a 64MHz clock for USRP1 from 10MHz reference? I saw some discussion
of the TAPR board, but it’s no longer available. The jackson labs
firefox is drool worthy but totally out of budget, especially since I
need two.