I try either Mouser or Surplus Sales of Nebraska or Fair Radio. Then of course there is RadioDaze and HayseedHamfest and justradios. If anyone knows of a source for 8 to 10mf 1000V caps suitable for a johnson viking 2 please let me know. The units I've seen start at $35.
For the 8 to 10 mfd caps, you can use three 33 mfd at 450 volts in series.
http://www.tuberadios.com/capacitors Axial for $1.60 each, Radial $1.15 each