This seller has a 16RP4 and some projection CRTs, but more interestingly, also appears to have two NOS 2F21 monoscopes (http://www.akh.se/tubes/htm/2f21.htm)!
Those are the specialized CRTs that generate the Indian head test pattern.

http://www.bobandersen.com/images/misc/2F21.jpg

I wish I was closer to Virginia.

http://cgi.ebay.com/10-Antique-RCA-Dumont-Television-Tubes-/320650542351

(no affiliation)

The 5820 image Orthicon would be a nice item for a collector as well. :yes:
jr

Edit; found a pix
http://www.r-type.org/exhib/aab0053.htm

Oh yeah - that is nice!