Regarding similar designs

Dear all,

I am designing an RF preamp, and also the calibration standards. That means, each pcb has the exact same geometrical outline, as well as the exact same position of the connectors (which will be simple pin headers). These are six different designs (the preamp itself as well as calibrations standrs for open, short, through, isolation and load). Since the preamp operates at high frequency, I have to use ROGERS 4350B material. While checking prices, I found that each individual order will cost around $98, which in total would be around $600. Is there a way to save money? The size is 22.5 mm x 15 mm, so pretty small. I only need five pcbs of each calibration standard, however, I want to buy 25 preamp pcbs. So in total 30 pcbs.

Best regards,

John