Here's another idea... You might be able to find a machine at D.I. for $5 to $10, that might have the clamp you're looking for.
I just looked it up on Brewer Sewing Supply and it's made by Brother. The retail on it is $19.50. The part number is XZ0001151. Here's the description: NEEDLE CLAMP ONLY Brother XL5232 XR46. It fits on all of these different machines.
Babylock B15, B17, B21, BL37, BL6300, BL6800, - Bernette 50, 60, 70, 75 - Brother PS21, PS3700, PX100, PX200, PX300, XL5010, XL5011, XL5020, XL5021, XL5030, XL5031, XL5100, XL5130, XL5230, XL5232, XL5300, XL5340, XL5500, XL5600, XL5700, XL6040, XL6050, XL6060, XL6452, XL6562, XR46, XR52, XR65, XR65T, needle clamp only (other parts sold separatly to complete needle clamp #XZ0002051 needle clamp screw, #XA5718051 needle clamp pin, #XZ0005050 thread guide, #012400432 thread guide screw) - Alternative numbers 502030.55.80, 502030.61.45, 502030.63.10, XZ0001051, XZ0001121
Good Luck to you! If you can't find one, send me a private message, and I could order it for you.