Ok, I will do the best with this and maybe add steel plate to the back to add weight and strength.

I just received an offer from Chai for these components:

-2 HIWIN HG20 rails + 4 blocks hgh20CA ZA 1800mm
-2 HIWIN HG20 rails + 4 blocks hgh20CA ZA 1380mm
-2 C7 Ball screw RM2010 total length end machined 1760mm with ballnut
-1 C7 Ball screw RM2010 total length end machcined 1360mm with ballnut
-3 2010 Nut Housing
-3 Jaw Flexible Coupling 6.35mm*12mm (Ballscrew to NEMA23)
-3 BK15/BF15 P5 AC

Chai price is 656 usd Total. Air shipping cost is included.
Fred from BST Automation is USD1155.00 for the same items.

Is it normal to have a big difference?