Replacement for THK GSR20T LM Block and rails

C=30mm
B=20mm

I looked in the HIWIN catalogue, there is no LM Guide with a B dimension of 20mm and a C dimension of 30mm.

Is there a place that sells knockoff THK GSR20T guides.

I would prefer to save the $100-$300 cost of 1-3 new LM Guides.

(1 is definitely broken, 1 is potentially repairable, 1 is lost but potentially findable.)