I have six or eight manifolds, from simple vintage to Tech style DIN Isolation types.
Here's a new, never installed 300 BAR, DIN, Isolation valve for $85. Adjustable spread to properly fit 6.9" to 8" cylinders. Double o-rings between center section and valves provides secure sealing.
If you are looking for something different please contact me for photos and descriptions of others that are available from $50 and up. Please use email link or post inquiries here. No PM's please... I forget to check for them.