These sockets can be made for $3 each or less if you have some non-working tube equipment that you can scavage the sockets from. Even bought new the sockets should be $2 or so. Add to that a few machine bolts and nuts, a piece of wood for a base and a few feet of hookup wire and you have all you need.
Parts needed for each socket.
(1) 6.5" of 1x4 pine or poplar works well
(1) 8-32 x 1.25 machine screw
(3) 8-32 nut
(3) washers to fit the machine screws
(1) tube socket of the correct type
(2) 1"x .25 tube for socket support
(2) 1.5" wood screws that fit the socket mounting holes
(4) adhesive rubber feet
hookup wire (get some 600 volt insulation wire)
I picked up a box of 100 each of the machine screws, nuts and washers because they were cheaper that way.
Step 1: Cut wood to size for bases.
Use sand paper and smooth the cut ends and round over the sharp corners.
Most modern tubes have either 7, 8, or 9 pins.
Mark your base with the number of terminals you need. Marking for holes as shown, 1-1/8" horiz. and 1" vertically would server for any of the tubes and make a nice looking symmetrical project.
Drill the holes using an 11/64 size drill or what ever you have that will fit the machine screws. Drill the holes carefully and as straight up as possible. It would be a good idea to use a drill press.
Use the sandpaper again to clean up the holes.
You can finish the wood if desired. Spray lacquer would seal them and prevent them from absorbing moisture from the air. Most projects would not be bothered by this.